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34
06_text/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/06_text/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/06_text/00_content.ipynb)."
]
},
{
@ -30,7 +30,7 @@
}
},
"source": [
"In this chapter, we continue the study of the built-in data types. The next layer on top of numbers consists of **textual data** that are modeled primarily with the `str` type in Python. `str` objects are more complex than the numeric objects in [Chapter 5 <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/develop/05_numbers/00_content.ipynb) as they *consist* of an *arbitrary* and possibly large number of *individual* characters that may be chosen from *any* alphabet in the history of humankind. Luckily, Python abstracts away most of this complexity from us. However, after looking at the `str` type in great detail, we briefly introduce the `bytes` type at the end of this chapter to understand how characters are modeled in memory."
"In this chapter, we continue the study of the built-in data types. The next layer on top of numbers consists of **textual data** that are modeled primarily with the `str` type in Python. `str` objects are more complex than the numeric objects in [Chapter 5 <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/main/05_numbers/00_content.ipynb) as they *consist* of an *arbitrary* and possibly large number of *individual* characters that may be chosen from *any* alphabet in the history of humankind. Luckily, Python abstracts away most of this complexity from us. However, after looking at the `str` type in great detail, we briefly introduce the `bytes` type at the end of this chapter to understand how characters are modeled in memory."
]
},
{
@ -137,7 +137,7 @@
"source": [
"As seen before, a `str` object evaluates to itself in a literal notation with enclosing **single quotes** `'`.\n",
"\n",
"In [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#Value-/-(Semantic)-\"Meaning\"), we specify the double quotes `\"` convention this book follows. Yet, single quotes `'` and double quotes `\"` are *perfect* substitutes. We could use the reverse convention, as well. As [this discussion <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_so.png\">](https://stackoverflow.com/questions/56011/single-quotes-vs-double-quotes-in-python) shows, many programmers have *strong* opinions about such conventions. Consequently, the discussion was \"closed as not constructive\" by the moderators."
"In [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#Value-/-(Semantic)-\"Meaning\"), we specify the double quotes `\"` convention this book follows. Yet, single quotes `'` and double quotes `\"` are *perfect* substitutes. We could use the reverse convention, as well. As [this discussion <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_so.png\">](https://stackoverflow.com/questions/56011/single-quotes-vs-double-quotes-in-python) shows, many programmers have *strong* opinions about such conventions. Consequently, the discussion was \"closed as not constructive\" by the moderators."
]
},
{
@ -290,7 +290,7 @@
}
},
"source": [
"As an alternative to the literal notation, we may use the built-in [str() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/stdtypes.html#str) constructor to cast non-`str` objects as `str` ones. As [Chapter 11 <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/develop/11_classes/00_content.ipynb) reveals, basically any object in Python has a **text representation**. Because of that we may also pass `list` objects, the boolean `True` and `False`, or `None` to [str() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/stdtypes.html#str)."
"As an alternative to the literal notation, we may use the built-in [str() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/stdtypes.html#str) constructor to cast non-`str` objects as `str` ones. As [Chapter 11 <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/main/11_classes/00_content.ipynb) reveals, basically any object in Python has a **text representation**. Because of that we may also pass `list` objects, the boolean `True` and `False`, or `None` to [str() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/stdtypes.html#str)."
]
},
{
@ -456,7 +456,7 @@
}
},
"source": [
"As shown in the \"*Guessing a Coin Toss*\" 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:-Guessing-a-Coin-Toss), the built-in [input() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/functions.html#input) function displays a prompt to the user and returns whatever is entered as a `str` object. [input() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/functions.html#input) is in particular valuable when writing command-line tools."
"As shown in the \"*Guessing a Coin Toss*\" 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:-Guessing-a-Coin-Toss), the built-in [input() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/functions.html#input) function displays a prompt to the user and returns whatever is entered as a `str` object. [input() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/functions.html#input) is in particular valuable when writing command-line tools."
]
},
{
@ -571,7 +571,7 @@
}
},
"source": [
"[open() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/functions.html#open) returns a **[proxy <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_wiki.png\">](https://en.wikipedia.org/wiki/Proxy_pattern)** object of type `TextIOWrapper` that allows us to interact with the file on disk. `mode='r'` shows that we opened the file in read-only mode and `encoding='UTF-8'` is explained in detail in the [The `bytes` Type <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/develop/06_text/01_content.ipynb#The-bytes-Type) section at the end of this chapter."
"[open() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/functions.html#open) returns a **[proxy <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_wiki.png\">](https://en.wikipedia.org/wiki/Proxy_pattern)** object of type `TextIOWrapper` that allows us to interact with the file on disk. `mode='r'` shows that we opened the file in read-only mode and `encoding='UTF-8'` is explained in detail in the [The `bytes` Type <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/main/06_text/01_content.ipynb#The-bytes-Type) section at the end of this chapter."
]
},
{
@ -1010,7 +1010,7 @@
}
},
"source": [
"Using syntax familiar from [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#The-try-Statement) to explain what the `with open(...) as file:` does above, we provide an alternative formulation with a `try` statement below: The `finally`-branch is *always* executed, even if an exception is raised inside the `for`-loop. Therefore, `file` is sure to be closed too. However, this formulation is somewhat less expressive."
"Using syntax familiar from [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#The-try-Statement) to explain what the `with open(...) as file:` does above, we provide an alternative formulation with a `try` statement below: The `finally`-branch is *always* executed, even if an exception is raised inside the `for`-loop. Therefore, `file` is sure to be closed too. However, this formulation is somewhat less expressive."
]
},
{
@ -1373,7 +1373,7 @@
}
},
"source": [
"A **sequence** is yet another *abstract* concept (cf., the \"*Containers vs. Iterables*\" section 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)).\n",
"A **sequence** is yet another *abstract* concept (cf., the \"*Containers vs. Iterables*\" section 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)).\n",
"\n",
"It unifies *four* [orthogonal <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_wiki.png\">](https://en.wikipedia.org/wiki/Orthogonality) (i.e., \"independent\") concepts into one bigger idea: Any data type, such as `str`, is considered a sequence if it\n",
"\n",
@ -1382,11 +1382,11 @@
"3. can be **iterated** over\n",
"4. in a *predictable* **order**.\n",
"\n",
"[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) formalizes these concepts in great detail. Here, we keep our focus on the `str` type that historically received its name as it models a **[string of characters <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_wiki.png\">](https://en.wikipedia.org/wiki/String_%28computer_science%29)**. *String* is simply another term for *sequence* in the computer science literature.\n",
"[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) formalizes these concepts in great detail. Here, we keep our focus on the `str` type that historically received its name as it models a **[string of characters <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_wiki.png\">](https://en.wikipedia.org/wiki/String_%28computer_science%29)**. *String* is simply another term for *sequence* in the computer science literature.\n",
"\n",
"Another example of a sequence is the `list` type. Because of that, `str` objects may be treated like `list` objects in many situations.\n",
"\n",
"Below, the built-in [len() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/functions.html#len) function tells us how many characters make up `text`. [len() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/functions.html#len) would not work with an \"infinite\" object. As anything modeled in a program must fit into a computer's finite memory, there cannot exist truly infinite objects; however, [Chapter 8 <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#Iterators-vs.-Iterables) introduces specialized iterable data types that can be used to model an *infinite* series of \"things\" and that, consequently, have no concept of \"length.\""
"Below, the built-in [len() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/functions.html#len) function tells us how many characters make up `text`. [len() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/functions.html#len) would not work with an \"infinite\" object. As anything modeled in a program must fit into a computer's finite memory, there cannot exist truly infinite objects; however, [Chapter 8 <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#Iterators-vs.-Iterables) introduces specialized iterable data types that can be used to model an *infinite* series of \"things\" and that, consequently, have no concept of \"length.\""
]
},
{
@ -1605,7 +1605,7 @@
}
},
"source": [
"As `str` objects are *ordered* and *finite*, we may **index** into them to obtain individual characters with the **indexing operator** `[]`. This is analogous to how we obtained individual elements of a `list` object in [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/03_content.ipynb#Who-am-I?-And-how-many?)."
"As `str` objects are *ordered* and *finite*, we may **index** into them to obtain individual characters with the **indexing operator** `[]`. This is analogous to how we obtained individual elements of a `list` object in [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/03_content.ipynb#Who-am-I?-And-how-many?)."
]
},
{
@ -2292,9 +2292,9 @@
}
},
"source": [
"Whereas elements of a `list` object *may* be *re-assigned*, as shortly hinted at in [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/03_content.ipynb#Who-am-I?-And-how-many?), this is *not* allowed for the individual characters of `str` objects. Once created, they can *not* be changed. Formally, we say that `str` objects are **immutable**. In that regard, they are like the numeric types in [Chapter 5 <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/develop/05_numbers/00_content.ipynb).\n",
"Whereas elements of a `list` object *may* be *re-assigned*, as shortly hinted at in [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/03_content.ipynb#Who-am-I?-And-how-many?), this is *not* allowed for the individual characters of `str` objects. Once created, they can *not* be changed. Formally, we say that `str` objects are **immutable**. In that regard, they are like the numeric types in [Chapter 5 <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/main/05_numbers/00_content.ipynb).\n",
"\n",
"On the contrary, objects that may be changed after creation, are called **mutable**. We already saw in [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/03_content.ipynb#Who-am-I?-And-how-many?) how mutable objects are more difficult to reason about for a beginner, in particular, if more than one variable references it. Yet, mutability does have its place in a programmer's toolbox, and we revisit this idea in the next chapters.\n",
"On the contrary, objects that may be changed after creation, are called **mutable**. We already saw in [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/03_content.ipynb#Who-am-I?-And-how-many?) how mutable objects are more difficult to reason about for a beginner, in particular, if more than one variable references it. Yet, mutability does have its place in a programmer's toolbox, and we revisit this idea in the next chapters.\n",
"\n",
"The `TypeError` indicates that `str` objects are *immutable*: Assignment to an index or a slice are *not* supported."
]
@ -3377,7 +3377,7 @@
}
},
"source": [
"As mentioned in [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#Operator-Overloading), the `+` and `*` operators are *overloaded* and used for **string concatenation**. They always create *new* `str` objects. That has nothing to do with the `str` type's immutability, but is the default behavior of operators."
"As mentioned in [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#Operator-Overloading), the `+` and `*` operators are *overloaded* and used for **string concatenation**. They always create *new* `str` objects. That has nothing to do with the `str` type's immutability, but is the default behavior of operators."
]
},
{
@ -3447,7 +3447,7 @@
}
},
"source": [
"The *relational* operators also work with `str` objects, another example of operator overloading. Comparison is done one character at a time in a pairwise fashion until the first pair differs or one operand ends. However, `str` objects are sorted in a \"weird\" way. For example, all upper case characters come before all lower case characters. The reason for that is given in the \"*Characters are Numbers with a Convention*\" sub-section in the [second 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/06_text/02_content.ipynb#Characters-are-Numbers-with-a-Convention) of this chapter."
"The *relational* operators also work with `str` objects, another example of operator overloading. Comparison is done one character at a time in a pairwise fashion until the first pair differs or one operand ends. However, `str` objects are sorted in a \"weird\" way. For example, all upper case characters come before all lower case characters. The reason for that is given in the \"*Characters are Numbers with a Convention*\" sub-section in the [second 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/06_text/02_content.ipynb#Characters-are-Numbers-with-a-Convention) of this chapter."
]
},
{
@ -3857,7 +3857,7 @@
}
},
"source": [
"The `%` operator that we saw in the context of modulo division in [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#%28Arithmetic%29-Operators) is overloaded with string interpolation when its first operand is a `str` object. The second operand consists of all expressions to be filled in. Format specifiers work with a `%` instead of curly braces and according to a different set of rules referred to as **[printf-style string formatting <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/stdtypes.html#printf-style-string-formatting)**. So, `{:.2f}` becomes `%.2f`.\n",
"The `%` operator that we saw in the context of modulo division in [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#%28Arithmetic%29-Operators) is overloaded with string interpolation when its first operand is a `str` object. The second operand consists of all expressions to be filled in. Format specifiers work with a `%` instead of curly braces and according to a different set of rules referred to as **[printf-style string formatting <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/stdtypes.html#printf-style-string-formatting)**. So, `{:.2f}` becomes `%.2f`.\n",
"\n",
"This way of string interpolation is the oldest and originates from the [C language <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_wiki.png\">](https://en.wikipedia.org/wiki/C_%28programming_language%29). It is still widely spread, but we should use one of the other two ways instead. We show it here mainly for completeness sake."
]
@ -3894,7 +3894,7 @@
}
},
"source": [
"To insert more than one expression, we must list them in order and between parenthesis `(` and `)`. As [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#The-tuple-Type) reveals, this literal syntax creates an object of type `tuple`. Also, to format an expression as text, we use the format specifier `%s`."
"To insert more than one expression, we must list them in order and between parenthesis `(` and `)`. As [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#The-tuple-Type) reveals, this literal syntax creates an object of type `tuple`. Also, to format an expression as text, we use the format specifier `%s`."
]
},
{

6
06_text/01_exercises_palindromes.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/06_text/01_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/06_text/01_exercises.ipynb)."
]
},
{
@ -18,7 +18,7 @@
"cell_type": "markdown",
"metadata": {},
"source": [
"The exercises below assume that you have read 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/06_text/00_content.ipynb) of Chapter 6.\n",
"The exercises below assume that you have read 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/06_text/00_content.ipynb) of Chapter 6.\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."
]
@ -38,7 +38,7 @@
"\n",
"In this exercise, you implement various functions that check if the given arguments are palindromes or not. We start with an iterative implementation and end with a recursive one.\n",
"\n",
"Conceptually, the first function, `unpythonic_palindrome()`, is similar to the \"*Is the square of a number in `[7, 11, 8, 5, 3, 12, 2, 6, 9, 10, 1, 4]` greater than `100`?*\" 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:-Is-the-square-of-a-number-in-[7,-11,-8,-5,-3,-12,-2,-6,-9,-10,-1,-4]-greater-than-100?): It assumes that the `text` argument is a palindrome (i.e., it initializes `is_palindrom` to `True`) and then checks in a `for`-loop if a pair of corresponding characters, `forward` and `backward`, contradicts that.\n",
"Conceptually, the first function, `unpythonic_palindrome()`, is similar to the \"*Is the square of a number in `[7, 11, 8, 5, 3, 12, 2, 6, 9, 10, 1, 4]` greater than `100`?*\" 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:-Is-the-square-of-a-number-in-[7,-11,-8,-5,-3,-12,-2,-6,-9,-10,-1,-4]-greater-than-100?): It assumes that the `text` argument is a palindrome (i.e., it initializes `is_palindrom` to `True`) and then checks in a `for`-loop if a pair of corresponding characters, `forward` and `backward`, contradicts that.\n",
"\n",
"**Q1**: How many iterations are needed in the `for`-loop? Take into account that `text` may contain an even or odd number of characters! Inside `unpythonic_palindrome()` below, write an expression whose result is assigned to `chars_to_check`!"
]

8
06_text/02_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/06_text/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/06_text/01_content.ipynb)."
]
},
{
@ -491,7 +491,7 @@
"source": [
"So far, we used the term **character** without any further consideration. In this section, we briefly look into what characters are and how they are modeled in software.\n",
"\n",
"[Chapter 5 <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/develop/05_numbers/00_content.ipynb) gives us an idea on how individual **bits** are used to express all types of numbers, from \"simple\" `int` objects to \"complex\" `float` ones. To model characters, another **layer of abstraction** is put on top of whole numbers. So, just as bits are used to express integers, they themselves are used to express characters."
"[Chapter 5 <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/main/05_numbers/00_content.ipynb) gives us an idea on how individual **bits** are used to express all types of numbers, from \"simple\" `int` objects to \"complex\" `float` ones. To model characters, another **layer of abstraction** is put on top of whole numbers. So, just as bits are used to express integers, they themselves are used to express characters."
]
},
{
@ -637,7 +637,7 @@
"\n",
"For example, the digit `5` is mapped to the number `53` in ASCII. The binary representation of `53` is `0b_11_0101` and the least significant four bits, `0101`, mean $5$. Similarly, the letter `\"E\"` is the fifth letter in the alphabet. It is encoded with the number `69` in ASCII, which is `0b_100_0101` in binary. And, the least significant bits, `0_0101`, mean $5$. Analogously, `\"e\"` is encoded with `101` in ASCII, which is `0b_110_0101` in binary. And, the least significant bits, `0_0101`, mean $5$ again. This encoding was chosen mainly because programmers \"in the old days\" needed to implement these encodings \"by hand.\" Python abstracts that logic away from its users.\n",
"\n",
"This encoding scheme is also the cause for the \"weird\" sorting in the \"*String Comparison*\" section 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/06_text/01_content.ipynb#String-Comparison) of this chapter, where `\"apple\"` comes *after* `\"Banana\"`. As `\"a\"` is encoded with `97` and `\"B\"` with `66`, `\"Banana\"` must of course be \"smaller\" than `\"apple\"` when comparison is done in a pairwise fashion of the individual characters."
"This encoding scheme is also the cause for the \"weird\" sorting in the \"*String Comparison*\" section 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/06_text/01_content.ipynb#String-Comparison) of this chapter, where `\"apple\"` comes *after* `\"Banana\"`. As `\"a\"` is encoded with `97` and `\"B\"` with `66`, `\"Banana\"` must of course be \"smaller\" than `\"apple\"` when comparison is done in a pairwise fashion of the individual characters."
]
},
{
@ -1991,7 +1991,7 @@
}
},
"source": [
"A best practice is to *always* specify the `encoding`, especially on computers running on Windows (cf., the talk by Łukasz Langa in the [Further Resources <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/develop/06_text/05_resources.ipynb#Unicode)) section at the end of this chapter.\n",
"A best practice is to *always* specify the `encoding`, especially on computers running on Windows (cf., the talk by Łukasz Langa in the [Further Resources <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_nb.png\">](https://nbviewer.jupyter.org/github/webartifex/intro-to-python/blob/main/06_text/05_resources.ipynb#Unicode)) section at the end of this chapter.\n",
"\n",
"Below is the first example involving [open() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/functions.html#open) one last time: It shows how *all* the contents of a text file should be read into one `str` object."
]

2
06_text/04_review.ipynb
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@ -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/06_text/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/06_text/01_content.ipynb) part of Chapter 6.\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/06_text/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/06_text/01_content.ipynb) part of Chapter 6.\n",
"\n",
"Be concise in your answers! Most questions can be answered in *one* sentence."
]

2
06_text/05_resources.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/06_text/05_resources.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/06_text/05_resources.ipynb)."
]
},
{