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10
08_mfr/00_content.ipynb
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@ -8,7 +8,7 @@
}
},
"source": [
"**Note**: Click on \"*Kernel*\" > \"*Restart Kernel and Clear All Outputs*\" in [JupyterLab](https://jupyterlab.readthedocs.io/en/stable/) *before* reading this notebook to reset its output. If you cannot run this file on your machine, you may want to open it [in the cloud <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_mb.png\">](https://mybinder.org/v2/gh/webartifex/intro-to-python/develop?urlpath=lab/tree/08_mfr/00_content.ipynb)."
"**Note**: Click on \"*Kernel*\" > \"*Restart Kernel and Clear All Outputs*\" in [JupyterLab](https://jupyterlab.readthedocs.io/en/stable/) *before* reading this notebook to reset its output. If you cannot run this file on your machine, you may want to open it [in the cloud <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_mb.png\">](https://mybinder.org/v2/gh/webartifex/intro-to-python/main?urlpath=lab/tree/08_mfr/00_content.ipynb)."
]
},
{
@ -32,9 +32,9 @@
"source": [
"In this chapter, we continue the study of sequential data by looking at memory efficient ways to process the elements in a sequence. That is an important topic for the data science practitioner who must be able to work with data that does *not* fit into a single computer's memory.\n",
"\n",
"As shown in [Chapter 4 <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/develop/04_iteration/02_content.ipynb#Containers-vs.-Iterables), both the `list` objects `[0, 1, 2, 3, 4]` and `[1, 3, 5, 7, 9]` on the one side and the `range` objects `range(5)` and `range(1, 10, 2)` on the other side allow us to loop over the same numbers. However, the latter two only create *one* `int` object in every iteration while the former two create *all* `int` objects before the loop even starts. In this aspect, we consider `range` objects to be \"rules\" in memory that know how to calculate the numbers *without* calculating them.\n",
"As shown in [Chapter 4 <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/main/04_iteration/02_content.ipynb#Containers-vs.-Iterables), both the `list` objects `[0, 1, 2, 3, 4]` and `[1, 3, 5, 7, 9]` on the one side and the `range` objects `range(5)` and `range(1, 10, 2)` on the other side allow us to loop over the same numbers. However, the latter two only create *one* `int` object in every iteration while the former two create *all* `int` objects before the loop even starts. In this aspect, we consider `range` objects to be \"rules\" in memory that know how to calculate the numbers *without* calculating them.\n",
"\n",
"In [Chapter 7 <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/develop/07_sequences/01_content.ipynb#The-list-Type), we see how the built-in [list() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/functions.html#func-list) constructor **materializes** the `range(1, 13)` object into the `list` object `[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12]`. In other words, we make `range(1, 13)` calculate *all* numbers at once and store them in a `list` object for further processing.\n",
"In [Chapter 7 <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/main/07_sequences/01_content.ipynb#The-list-Type), we see how the built-in [list() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/functions.html#func-list) constructor **materializes** the `range(1, 13)` object into the `list` object `[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12]`. In other words, we make `range(1, 13)` calculate *all* numbers at once and store them in a `list` object for further processing.\n",
"\n",
"In many cases, however, it is not necessary to do that, and, in this chapter, we look at other types of \"rules\" in memory and how we can compose different \"rules\" together to implement bigger computations.\n",
"\n",
@ -779,7 +779,7 @@
}
},
"source": [
"Using the [map() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/functions.html#map) and [filter() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/functions.html#filter) built-ins, we can quickly switch the order: Filter first and then transform the remaining elements. This variant equals the \"*A simple Filter*\" example in [Chapter 4 <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/develop/04_iteration/03_content.ipynb#Example:-A-simple-Filter). On the contrary, code with `for`-loops and `if` statements is more tedious to adapt. Additionally, `map` and `filter` objects loop \"at the C level\" and are a lot faster because of that. Because of that, experienced Pythonistas tend to *not* use explicit `for`-loops so often."
"Using the [map() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/functions.html#map) and [filter() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/functions.html#filter) built-ins, we can quickly switch the order: Filter first and then transform the remaining elements. This variant equals the \"*A simple Filter*\" example in [Chapter 4 <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/main/04_iteration/03_content.ipynb#Example:-A-simple-Filter). On the contrary, code with `for`-loops and `if` statements is more tedious to adapt. Additionally, `map` and `filter` objects loop \"at the C level\" and are a lot faster because of that. Because of that, experienced Pythonistas tend to *not* use explicit `for`-loops so often."
]
},
{
@ -1129,7 +1129,7 @@
"\n",
"Often, such functions are used *only once* in a program. However, the primary purpose of functions is to *reuse* them. In such cases, it makes more sense to define them \"anonymously\" right at the position where the first argument goes.\n",
"\n",
"As mentioned in [Chapter 2 <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/develop/02_functions/00_content.ipynb#Anonymous-Functions), we use `lambda` expressions to create `function` objects *without* a name referencing them.\n",
"As mentioned in [Chapter 2 <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/main/02_functions/00_content.ipynb#Anonymous-Functions), we use `lambda` expressions to create `function` objects *without* a name referencing them.\n",
"\n",
"So, the above `sum_alt()` function could be rewritten as a `lambda` expression like so ..."
]

22
08_mfr/01_content.ipynb
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@ -8,7 +8,7 @@
}
},
"source": [
"**Note**: Click on \"*Kernel*\" > \"*Restart Kernel and Clear All Outputs*\" in [JupyterLab](https://jupyterlab.readthedocs.io/en/stable/) *before* reading this notebook to reset its output. If you cannot run this file on your machine, you may want to open it [in the cloud <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_mb.png\">](https://mybinder.org/v2/gh/webartifex/intro-to-python/develop?urlpath=lab/tree/08_mfr/01_content.ipynb)."
"**Note**: Click on \"*Kernel*\" > \"*Restart Kernel and Clear All Outputs*\" in [JupyterLab](https://jupyterlab.readthedocs.io/en/stable/) *before* reading this notebook to reset its output. If you cannot run this file on your machine, you may want to open it [in the cloud <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_mb.png\">](https://mybinder.org/v2/gh/webartifex/intro-to-python/main?urlpath=lab/tree/08_mfr/01_content.ipynb)."
]
},
{
@ -30,7 +30,7 @@
}
},
"source": [
"After introducing the Map-Filter-Reduce paradigm in the [first part <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/develop/08_mfr/00_content.ipynb) of this chapter, we first see how `list` comprehensions can replace the [map() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/functions.html#map) and [filter() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/functions.html#filter) built-ins in many cases. Then, we learn how `generator` expressions are like `list` comprehensions *without* using the memory. We end this part with a short discussion of the built-in [all() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/functions.html#all) and [any() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/functions.html#any) functions."
"After introducing the Map-Filter-Reduce paradigm in the [first part <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/main/08_mfr/00_content.ipynb) of this chapter, we first see how `list` comprehensions can replace the [map() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/functions.html#map) and [filter() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/functions.html#filter) built-ins in many cases. Then, we learn how `generator` expressions are like `list` comprehensions *without* using the memory. We end this part with a short discussion of the built-in [all() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/functions.html#all) and [any() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/functions.html#any) functions."
]
},
{
@ -52,7 +52,7 @@
}
},
"source": [
"Consider again the original \"*A simple Filter*\" example from [Chapter 4 <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/develop/04_iteration/03_content.ipynb#Example:-A-simple-Filter), re-written such that both the mapping and the filtering are done in *one* `for`-loop instead of the *two* above."
"Consider again the original \"*A simple Filter*\" example from [Chapter 4 <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/main/04_iteration/03_content.ipynb#Example:-A-simple-Filter), re-written such that both the mapping and the filtering are done in *one* `for`-loop instead of the *two* above."
]
},
{
@ -156,7 +156,7 @@
"source": [
"A list comprehension may always be used in a place where otherwise a `list` object would work.\n",
"\n",
"For example, let's rewrite the \"*A simple Filter*\" example from [Chapter 4 <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/develop/04_iteration/03_content.ipynb#Example:-A-simple-Filter) in just one line. As a caveat, the code below *materializes* all elements in memory *before* summing them up, and may, therefore, cause a `MemoryError` when executed with a bigger `numbers` list. We see with [PythonTutor <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](http://pythontutor.com/visualize.html#code=numbers%20%3D%20range%281,%2013%29%0Aresult%20%3D%20sum%28%5B%28n%20**%202%29%20%2B%201%20for%20n%20in%20numbers%20if%20n%20%25%202%20%3D%3D%200%5D%29&cumulative=false&curstr=0&heapPrimitives=nevernest&mode=display&origin=opt-frontend.js&py=3&rawInputLstJSON=%5B%5D&textReferences=false) how a `list` object exists in memory at step 17 and then \"gets lost\" right after. As the next section shows, this downside may be mitigated."
"For example, let's rewrite the \"*A simple Filter*\" example from [Chapter 4 <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/main/04_iteration/03_content.ipynb#Example:-A-simple-Filter) in just one line. As a caveat, the code below *materializes* all elements in memory *before* summing them up, and may, therefore, cause a `MemoryError` when executed with a bigger `numbers` list. We see with [PythonTutor <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](http://pythontutor.com/visualize.html#code=numbers%20%3D%20range%281,%2013%29%0Aresult%20%3D%20sum%28%5B%28n%20**%202%29%20%2B%201%20for%20n%20in%20numbers%20if%20n%20%25%202%20%3D%3D%200%5D%29&cumulative=false&curstr=0&heapPrimitives=nevernest&mode=display&origin=opt-frontend.js&py=3&rawInputLstJSON=%5B%5D&textReferences=false) how a `list` object exists in memory at step 17 and then \"gets lost\" right after. As the next section shows, this downside may be mitigated."
]
},
{
@ -639,7 +639,7 @@
}
},
"source": [
"To find the overall product, we *unpack* the list comprehension into the `product()` function from the \"*Function Definitions & Calls*\" sub-section in [Chapter 7 <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/develop/07_sequences/03_content.ipynb#Function-Definitions-&-Calls)."
"To find the overall product, we *unpack* the list comprehension into the `product()` function from the \"*Function Definitions & Calls*\" sub-section in [Chapter 7 <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/main/07_sequences/03_content.ipynb#Function-Definitions-&-Calls)."
]
},
{
@ -766,7 +766,7 @@
"source": [
"Because of the high memory consumption, Pythonistas avoid materialized `list` objects, and, thus, also `list` comprehensions, whenever possible. Instead, they prefer to work with **[`generator` expressions <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/reference/expressions.html#generator-expressions)**. Syntactically, they work like list comprehensions except that parentheses, `(` and `)`, replace brackets, `[` and `]`.\n",
"\n",
"Let's go back to the original \"*A simple Filter*\" example from [Chapter 4 <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/develop/04_iteration/03_content.ipynb#Example:-A-simple-Filter) one more time, apply the transformation $y := x^2 + 1$ to all even `numbers`, and sum them up."
"Let's go back to the original \"*A simple Filter*\" example from [Chapter 4 <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/main/04_iteration/03_content.ipynb#Example:-A-simple-Filter) one more time, apply the transformation $y := x^2 + 1$ to all even `numbers`, and sum them up."
]
},
{
@ -1050,7 +1050,7 @@
}
},
"source": [
"`generator` objects work just like the `map` and `filter` objects in the [first part <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/develop/08_mfr/00_content.ipynb) of this chapter. So, with the [next() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/functions.html#next) function, we can generate elements one by one."
"`generator` objects work just like the `map` and `filter` objects in the [first part <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/main/08_mfr/00_content.ipynb) of this chapter. So, with the [next() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/functions.html#next) function, we can generate elements one by one."
]
},
{
@ -1564,7 +1564,7 @@
"source": [
"Now, the first of the two alternative solutions may be more appealing to many readers. In general, many practitioners seem to dislike `lambda` expressions.\n",
"\n",
"In the first solution, we *unpack* the elements produced by `(1 + (x / y) for x in first for y in second)` into the `product()` function from the \"*Function Definitions & Calls*\" sub-section in [Chapter 7 <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/develop/07_sequences/03_content.ipynb#Function-Definitions-&-Calls). However, inside `product()`, the elements are *packed* into `args`, a *materialized* `tuple` object! So, all the memory efficiency gained by using a generator expression is lost! [PythonTutor <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](http://pythontutor.com/visualize.html#code=def%20product%28*args%29%3A%0A%20%20%20%20result%20%3D%20args%5B0%5D%0A%20%20%20%20for%20arg%20in%20args%5B1%3A%5D%3A%0A%20%20%20%20%20%20%20%20result%20*%3D%20arg%0A%20%20%20%20return%20result%0A%0Afirst%20%3D%20range%2810,%2031,%2010%29%0Asecond%20%3D%20range%2840,%2061,%2010%29%0A%0Aresult%20%3D%20product%28*%281%20%2B%20%28x%20/%20y%29%20for%20x%20in%20first%20for%20y%20in%20second%29%29&cumulative=false&curstr=0&heapPrimitives=nevernest&mode=display&origin=opt-frontend.js&py=3&rawInputLstJSON=%5B%5D&textReferences=false) shows how a `tuple` object exists in steps 38-58."
"In the first solution, we *unpack* the elements produced by `(1 + (x / y) for x in first for y in second)` into the `product()` function from the \"*Function Definitions & Calls*\" sub-section in [Chapter 7 <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/main/07_sequences/03_content.ipynb#Function-Definitions-&-Calls). However, inside `product()`, the elements are *packed* into `args`, a *materialized* `tuple` object! So, all the memory efficiency gained by using a generator expression is lost! [PythonTutor <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](http://pythontutor.com/visualize.html#code=def%20product%28*args%29%3A%0A%20%20%20%20result%20%3D%20args%5B0%5D%0A%20%20%20%20for%20arg%20in%20args%5B1%3A%5D%3A%0A%20%20%20%20%20%20%20%20result%20*%3D%20arg%0A%20%20%20%20return%20result%0A%0Afirst%20%3D%20range%2810,%2031,%2010%29%0Asecond%20%3D%20range%2840,%2061,%2010%29%0A%0Aresult%20%3D%20product%28*%281%20%2B%20%28x%20/%20y%29%20for%20x%20in%20first%20for%20y%20in%20second%29%29&cumulative=false&curstr=0&heapPrimitives=nevernest&mode=display&origin=opt-frontend.js&py=3&rawInputLstJSON=%5B%5D&textReferences=false) shows how a `tuple` object exists in steps 38-58."
]
},
{
@ -1656,13 +1656,13 @@
}
},
"source": [
"With the new concepts in this chapter, let's rewrite the book's introductory \"*Averaging all even Numbers in a List*\" example from [Chapter 1 <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/develop/01_elements/00_content.ipynb#Example:-Averaging-all-even-Numbers-in-a-List) such that it efficiently handles a large sequence of numbers. We continue from its latest implementation, the `average_evens()` function in the \"*Keyword-only Arguments*\" section in [Chapter 2 <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/develop/02_functions/00_content.ipynb#Keyword-only-Arguments).\n",
"With the new concepts in this chapter, let's rewrite the book's introductory \"*Averaging all even Numbers in a List*\" example from [Chapter 1 <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/main/01_elements/00_content.ipynb#Example:-Averaging-all-even-Numbers-in-a-List) such that it efficiently handles a large sequence of numbers. We continue from its latest implementation, the `average_evens()` function in the \"*Keyword-only Arguments*\" section in [Chapter 2 <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/main/02_functions/00_content.ipynb#Keyword-only-Arguments).\n",
"\n",
"We assume that `average_evens()` is called with a *finite* and *iterable* object that generates a **stream** of numeric objects that can be cast as `int` objects. After all, the idea of even and odd numbers makes sense only in the context of whole numbers.\n",
"\n",
"The `generator` expression `(round(n) for n in numbers)` implements the type casting, and, when it is evaluated during a function call, *nothing* happens except that a `generator` object is assigned to `integers`. Then, with the [reduce() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/functools.html#functools.reduce) function from the [functools <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/functools.html) module, we *simultaneously* add up *and* count the even numbers with the `generator` object to which the inner `generator` expression `((n, 1) for n in integers if n % 2 == 0)` evaluates to. That `generator` object takes the `integers` generator as its source and produces `tuple` objects consisting of the next *even* number in line and `1`. Two such `tuple` objects are then iteratively passed to the `function` object to which the `lambda` expression evaluates to. `x` represents the total and the count of the even numbers processed so far, while `y`'s first element, `y[0]`, is the next *even* number to be added to the running total. The result of calling [reduce() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/functools.html#functools.reduce) is again a `tuple` object, namely the final `total` and `count`. Lastly, we calculate the simple average and scale it.\n",
"\n",
"In summary, this implementation of `average_evens()` does *not* keep materialized `list` objects internally like its predecessors in [Chapter 2 <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/develop/02_functions/00_content.ipynb) but processes the elements of the `numbers` argument on a one-by-one basis."
"In summary, this implementation of `average_evens()` does *not* keep materialized `list` objects internally like its predecessors in [Chapter 2 <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/main/02_functions/00_content.ipynb) but processes the elements of the `numbers` argument on a one-by-one basis."
]
},
{
@ -2040,7 +2040,7 @@
}
},
"source": [
"[all() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/functions.html#all) can be viewed as syntactic sugar replacing a `for`-loop: Internally, [all() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/functions.html#all) implements the *short-circuiting* strategy explained in [Chapter 3 <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/develop/03_conditionals/00_content.ipynb#Short-Circuiting), and we mimic that by testing for the *opposite* condition in the `if` statement and stopping the `for`-loop early with the `break` statement. In the worst case, if `threshold` were, for example, `150`, we would loop over *all* elements in the `iterable` argument, which must be *finite* for the code to work. So, [all() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/functions.html#all) is a *linear search* in disguise."
"[all() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/functions.html#all) can be viewed as syntactic sugar replacing a `for`-loop: Internally, [all() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/functions.html#all) implements the *short-circuiting* strategy explained in [Chapter 3 <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/main/03_conditionals/00_content.ipynb#Short-Circuiting), and we mimic that by testing for the *opposite* condition in the `if` statement and stopping the `for`-loop early with the `break` statement. In the worst case, if `threshold` were, for example, `150`, we would loop over *all* elements in the `iterable` argument, which must be *finite* for the code to work. So, [all() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/functions.html#all) is a *linear search* in disguise."
]
},
{

8
08_mfr/02_exercises_outliers.ipynb
View file

@ -4,7 +4,7 @@
"cell_type": "markdown",
"metadata": {},
"source": [
"**Note**: Click on \"*Kernel*\" > \"*Restart Kernel and Run All*\" in [JupyterLab](https://jupyterlab.readthedocs.io/en/stable/) *after* finishing the exercises to ensure that your solution runs top to bottom *without* any errors. If you cannot run this file on your machine, you may want to open it [in the cloud <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_mb.png\">](https://mybinder.org/v2/gh/webartifex/intro-to-python/develop?urlpath=lab/tree/08_mfr/02_exercises.ipynb)."
"**Note**: Click on \"*Kernel*\" > \"*Restart Kernel and Run All*\" in [JupyterLab](https://jupyterlab.readthedocs.io/en/stable/) *after* finishing the exercises to ensure that your solution runs top to bottom *without* any errors. If you cannot run this file on your machine, you may want to open it [in the cloud <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_mb.png\">](https://mybinder.org/v2/gh/webartifex/intro-to-python/main?urlpath=lab/tree/08_mfr/02_exercises.ipynb)."
]
},
{
@ -18,7 +18,7 @@
"cell_type": "markdown",
"metadata": {},
"source": [
"The exercises below assume that you have read the [first <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/develop/08_mfr/00_content.ipynb) and [second <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/develop/08_mfr/01_content.ipynb) part of Chapter 8.\n",
"The exercises below assume that you have read the [first <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/main/08_mfr/00_content.ipynb) and [second <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/main/08_mfr/01_content.ipynb) part of Chapter 8.\n",
"\n",
"The `...`'s in the code cells indicate where you need to fill in code snippets. The number of `...`'s within a code cell give you a rough idea of how many lines of code are needed to solve the task. You should not need to create any additional code cells for your final solution. However, you may want to use temporary code cells to try out some ideas."
]
@ -335,7 +335,7 @@
"cell_type": "markdown",
"metadata": {},
"source": [
"We provide a `stream` module with a `data` object that models an *infinite* **stream** of data (cf., the [*stream.py* <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_gh.png\">](https://github.com/webartifex/intro-to-python/blob/develop/08_mfr/stream.py) file in the repository)."
"We provide a `stream` module with a `data` object that models an *infinite* **stream** of data (cf., the [*stream.py* <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_gh.png\">](https://github.com/webartifex/intro-to-python/blob/main/08_mfr/stream.py) file in the repository)."
]
},
{
@ -574,7 +574,7 @@
"source": [
"**Q10.2**: Just as in `standardized()`, write a `generator` expression that produces z-scores one by one! However, instead of just generating a z-score, the resulting `generator` object should produce `tuple` objects consisting of a \"raw\" number from `data` and its z-score.\n",
"\n",
"Hint: Look at the revisited \"*Averaging Even Numbers*\" example in [Chapter 7 <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/develop/07_sequences/01_content.ipynb#Example:-Averaging-all-even-Numbers-in-a-List-%28revisited%29) for some inspiration, which also contains a `generator` expression producing `tuple` objects."
"Hint: Look at the revisited \"*Averaging Even Numbers*\" example in [Chapter 7 <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/main/07_sequences/01_content.ipynb#Example:-Averaging-all-even-Numbers-in-a-List-%28revisited%29) for some inspiration, which also contains a `generator` expression producing `tuple` objects."
]
},
{

8
08_mfr/03_exercises_un-packing.ipynb
View file

@ -4,7 +4,7 @@
"cell_type": "markdown",
"metadata": {},
"source": [
"**Note**: Click on \"*Kernel*\" > \"*Restart Kernel and Run All*\" in [JupyterLab](https://jupyterlab.readthedocs.io/en/stable/) *after* finishing the exercises to ensure that your solution runs top to bottom *without* any errors. If you cannot run this file on your machine, you may want to open it [in the cloud <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_mb.png\">](https://mybinder.org/v2/gh/webartifex/intro-to-python/develop?urlpath=lab/tree/08_mfr/03_exercises.ipynb)."
"**Note**: Click on \"*Kernel*\" > \"*Restart Kernel and Run All*\" in [JupyterLab](https://jupyterlab.readthedocs.io/en/stable/) *after* finishing the exercises to ensure that your solution runs top to bottom *without* any errors. If you cannot run this file on your machine, you may want to open it [in the cloud <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_mb.png\">](https://mybinder.org/v2/gh/webartifex/intro-to-python/main?urlpath=lab/tree/08_mfr/03_exercises.ipynb)."
]
},
{
@ -18,7 +18,7 @@
"cell_type": "markdown",
"metadata": {},
"source": [
"The exercises below assume that you have read the [first <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/develop/08_mfr/00_content.ipynb) and [second <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/develop/08_mfr/01_content.ipynb) part of Chapter 8.\n",
"The exercises below assume that you have read the [first <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/main/08_mfr/00_content.ipynb) and [second <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/main/08_mfr/01_content.ipynb) part of Chapter 8.\n",
"\n",
"The `...`'s in the code cells indicate where you need to fill in code snippets. The number of `...`'s within a code cell give you a rough idea of how many lines of code are needed to solve the task. You should not need to create any additional code cells for your final solution. However, you may want to use temporary code cells to try out some ideas."
]
@ -34,7 +34,7 @@
"cell_type": "markdown",
"metadata": {},
"source": [
"**Q1**: Copy your solution to **Q10** from the \"*Packing & Unpacking with Functions*\" exercise in [Chapter 7 <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/develop/07_sequences/04_exercises.ipynb) into the code cell below!"
"**Q1**: Copy your solution to **Q10** from the \"*Packing & Unpacking with Functions*\" exercise in [Chapter 7 <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/main/07_sequences/04_exercises.ipynb) into the code cell below!"
]
},
{
@ -152,7 +152,7 @@
"\n",
"**Q4**: Click through the following code cells and observe what they do!\n",
"\n",
"The [*stream.py* <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_gh.png\">](https://github.com/webartifex/intro-to-python/blob/develop/08_mfr/stream.py) module in the book's repository provides a `make_finite_stream()` function. It is a *factory* function creating objects of type `generator` that we use to model *streaming* data."
"The [*stream.py* <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_gh.png\">](https://github.com/webartifex/intro-to-python/blob/main/08_mfr/stream.py) module in the book's repository provides a `make_finite_stream()` function. It is a *factory* function creating objects of type `generator` that we use to model *streaming* data."
]
},
{

10
08_mfr/04_content.ipynb
View file

@ -8,7 +8,7 @@
}
},
"source": [
"**Note**: Click on \"*Kernel*\" > \"*Restart Kernel and Clear All Outputs*\" in [JupyterLab](https://jupyterlab.readthedocs.io/en/stable/) *before* reading this notebook to reset its output. If you cannot run this file on your machine, you may want to open it [in the cloud <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_mb.png\">](https://mybinder.org/v2/gh/webartifex/intro-to-python/develop?urlpath=lab/tree/08_mfr/04_content.ipynb)."
"**Note**: Click on \"*Kernel*\" > \"*Restart Kernel and Clear All Outputs*\" in [JupyterLab](https://jupyterlab.readthedocs.io/en/stable/) *before* reading this notebook to reset its output. If you cannot run this file on your machine, you may want to open it [in the cloud <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_mb.png\">](https://mybinder.org/v2/gh/webartifex/intro-to-python/main?urlpath=lab/tree/08_mfr/04_content.ipynb)."
]
},
{
@ -30,7 +30,7 @@
}
},
"source": [
"Similarly to how we classify different *concrete* data types like `list` or `str` by how they behave *abstractly* in a given context in [Chapter 7 <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/develop/07_sequences/00_content.ipynb#Collections-vs.-Sequences), we also do so for the data types we have introduced in this chapter."
"Similarly to how we classify different *concrete* data types like `list` or `str` by how they behave *abstractly* in a given context in [Chapter 7 <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/main/07_sequences/00_content.ipynb#Collections-vs.-Sequences), we also do so for the data types we have introduced in this chapter."
]
},
{
@ -174,7 +174,7 @@
}
},
"source": [
"Furthermore, we sharpen our definition of an *iterable* from [Chapter 7 <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/develop/07_sequences/00_content.ipynb#Collections-vs.-Sequences): Just as we define an *iterator* to be any object that supports the [next() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/functions.html#next) function, we define an *iterable* to be any object that supports the built-in [iter() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/functions.html#iter) function.\n",
"Furthermore, we sharpen our definition of an *iterable* from [Chapter 7 <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/main/07_sequences/00_content.ipynb#Collections-vs.-Sequences): Just as we define an *iterator* to be any object that supports the [next() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/functions.html#next) function, we define an *iterable* to be any object that supports the built-in [iter() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/functions.html#iter) function.\n",
"\n",
"The confused reader may now be wondering how the two concepts relate to each other.\n",
"\n",
@ -780,7 +780,7 @@
}
},
"source": [
"In [Chapter 4 <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/develop/04_iteration/02_content.ipynb#The-for-Statement), we argue that the `for` statement is syntactic sugar, replacing the `while` statement in many common scenarios. In particular, a `for`-loop saves us two tasks: Managing an index variable *and* obtaining the individual elements by indexing. In this sub-section, we look at a more realistic picture, using the new terminology as well.\n",
"In [Chapter 4 <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/main/04_iteration/02_content.ipynb#The-for-Statement), we argue that the `for` statement is syntactic sugar, replacing the `while` statement in many common scenarios. In particular, a `for`-loop saves us two tasks: Managing an index variable *and* obtaining the individual elements by indexing. In this sub-section, we look at a more realistic picture, using the new terminology as well.\n",
"\n",
"Let's print out the elements of a `list` object as the *iterable* being looped over."
]
@ -924,7 +924,7 @@
}
},
"source": [
"Now that we know the concept of an *iterator*, let's compare some of the built-ins introduced in [Chapter 7 <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/develop/07_sequences/00_content.ipynb) in detail and make sure we understand what is going on in memory. This section also serves as a summary of all the concepts in this chapter.\n",
"Now that we know the concept of an *iterator*, let's compare some of the built-ins introduced in [Chapter 7 <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/main/07_sequences/00_content.ipynb) in detail and make sure we understand what is going on in memory. This section also serves as a summary of all the concepts in this chapter.\n",
"\n",
"We use two simple examples, `numbers` and `memoryless`: `numbers` creates *thirteen* objects in memory and `memoryless` only *one* (cf., [PythonTutor <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](http://pythontutor.com/visualize.html#code=numbers%20%3D%20%5B7,%2011,%208,%205,%203,%2012,%202,%206,%209,%2010,%201,%204%5D%0Amemoryless%20%3D%20range%281,%2013%29&cumulative=false&curstr=2&heapPrimitives=nevernest&mode=display&origin=opt-frontend.js&py=3&rawInputLstJSON=%5B%5D&textReferences=false))."
]

2
08_mfr/06_review.ipynb
View file

@ -11,7 +11,7 @@
"cell_type": "markdown",
"metadata": {},
"source": [
"The questions below assume that you have read the [first <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/develop/08_mfr/00_content.ipynb), [second <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/develop/08_mfr/01_content.ipynb), and [third <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/develop/08_mfr/04_content.ipynb) part in Chapter 8.\n",
"The questions below assume that you have read the [first <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/main/08_mfr/00_content.ipynb), [second <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/main/08_mfr/01_content.ipynb), and [third <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/main/08_mfr/04_content.ipynb) part in Chapter 8.\n",
"\n",
"Be concise in your answers! Most questions can be answered in *one* sentence."
]