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After refurbishing the project we prepare a new relaease.
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Alexander Hess 2024-04-08 22:13:31 +02:00
commit 94e5112f10
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GPG key ID: 344EA5AB10D868E0
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12
01_elements/03_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/01_elements/03_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/01_elements/03_content.ipynb)."
]
},
{
@ -367,7 +367,7 @@
}
},
"source": [
"Some variables magically exist when a Python process is started or are added by Jupyter. We may safely ignore the former until [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) and the latter for good."
"Some variables magically exist when a Python process is started or are added by Jupyter. We may safely ignore the former until [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) and the latter for good."
]
},
{
@ -687,7 +687,7 @@
}
},
"source": [
"Variables with leading and trailing double underscores, referred to as **dunder** in Python jargon, are used for built-in functionalities and to implement object-oriented features as we see in [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). We must *not* use this style for variables!"
"Variables with leading and trailing double underscores, referred to as **dunder** in Python jargon, are used for built-in functionalities and to implement object-oriented features as we see in [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). We must *not* use this style for variables!"
]
},
{
@ -968,7 +968,7 @@
"source": [
"Let's change the first element of `x`.\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#The-list-Type) discusses lists in more depth. For now, let's view a `list` object as some sort of **container** that holds an arbitrary number of references to other objects and treat the brackets `[]` attached to it as yet another operator, namely the **indexing operator**. So, `x[0]` instructs Python to first follow the reference from the global list of all names to the `x` object. Then, it follows the first reference it finds there to the `1` object we put in the list. The indexing operator must be an operator as we merely *read* the first element and do not change anything in memory permanently.\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#The-list-Type) discusses lists in more depth. For now, let's view a `list` object as some sort of **container** that holds an arbitrary number of references to other objects and treat the brackets `[]` attached to it as yet another operator, namely the **indexing operator**. So, `x[0]` instructs Python to first follow the reference from the global list of all names to the `x` object. Then, it follows the first reference it finds there to the `1` object we put in the list. The indexing operator must be an operator as we merely *read* the first element and do not change anything in memory permanently.\n",
"\n",
"Python **begins counting at 0**. This is not the case for many other languages, for example, [MATLAB <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_wiki.png\">](https://en.wikipedia.org/wiki/MATLAB), [R <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_wiki.png\">](https://en.wikipedia.org/wiki/R_%28programming_language%29), or [Stata <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_wiki.png\">](https://en.wikipedia.org/wiki/Stata). To understand why this makes sense, see this short [note](https://www.cs.utexas.edu/users/EWD/transcriptions/EWD08xx/EWD831.html) by one of the all-time greats in computer science, the late [Edsger Dijkstra <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_wiki.png\">](https://en.wikipedia.org/wiki/Edsger_W._Dijkstra)."
]
@ -1144,7 +1144,7 @@
"\n",
"In simple words, anything that may be used on the *right-hand* side of an assignment statement without creating a `SyntaxError` is an expression.\n",
"\n",
"What we have said about *individual* operators before, namely that they have *no* permanent side effects in memory, actually belongs here, to begin with: The absence of any *permanent* side effects is the characteristic property of expressions, and all the code cells in the \"*(Arithmetic) Operators*\" 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/01_elements/00_content.ipynb#%28Arithmetic%29-Operators) of this chapter are examples of expressions.\n",
"What we have said about *individual* operators before, namely that they have *no* permanent side effects in memory, actually belongs here, to begin with: The absence of any *permanent* side effects is the characteristic property of expressions, and all the code cells in the \"*(Arithmetic) Operators*\" 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/01_elements/00_content.ipynb#%28Arithmetic%29-Operators) of this chapter are examples of expressions.\n",
"\n",
"The simplest possible expressions contain only one variable or literal. The output below a code cell is Jupyter's way of returning the reference to the object to us!\n",
"\n",
@ -1414,7 +1414,7 @@
}
},
"source": [
"... calling the built-in [print() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/functions.html#print) function does *neither* change the memory *nor* evaluate to an object (disregarding the `None` object explained 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#Function-Definitions)). We could view changing the computer's screen as a side effect but this is outside of Python's memory!\n",
"... calling the built-in [print() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/functions.html#print) function does *neither* change the memory *nor* evaluate to an object (disregarding the `None` object explained 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#Function-Definitions)). We could view changing the computer's screen as a side effect but this is outside of Python's memory!\n",
"\n",
"Also, the cell below has *no* output! It only looks like it does as Jupyter redirects whatever [print() <img height=\"12\" style=\"display: inline-block\" src=\"../static/link/to_py.png\">](https://docs.python.org/3/library/functions.html#print) writes to the \"screen\" to below a cell. We see a difference to the expressions above in that there are no brackets `[...]` next to the output showing the execution count number."
]