Python - Revision history

Hdridder: /* collections */

2025-12-11T08:07:31Z

collections

@@ Line 160: / Line 160: @@
 <syntaxhighlight lang=python>from collections import defaultdict</syntaxhighlight>
-;WARNING; In a [[Python:DataTypes#Dictionary_or_dict|dictionary]] created with defaultdict a key will be added when you try to read a non-existing lower key.
+;WARNING; In a [[Python:DataTypes#Dictionary_or_dict|dictionary]] created with defaultdict a key will be added when you try to read a non-existing lower key. See [[Python:DataTypes#Dictionary or dict]].
 ==itertools==

2025-12-11T07:54:07Z

collections

← Older revision		Revision as of 07:54, 11 December 2025
Line 166:		Line 166:
	print(adict[key1][key2]) # This will create adict[key1]		print(adict[key1][key2]) # This will create adict[key1]
	</syntaxhighlight>		</syntaxhighlight>

			;bdict = dict(adict)
			:bdict will be an ordinary dict.
	;adict = defaultdict(<type>)		;adict = defaultdict(<type>)
	:Create a dictionary key of the provided type automatically when it is used (see WARNINIG above). Use this to avoid checking if a key already exists before you populate it. If you do not provide <type> you can put in anything.		:Create a dictionary key of the provided type automatically when it is used (see WARNINIG above). Use this to avoid checking if a key already exists before you populate it. If you do not provide <type> you can put in anything.
Line 172:		Line 175:
	:Use lambda function to handle multilevel dictionaries		:Use lambda function to handle multilevel dictionaries
	:NOTE: For 2 levels, and 2nd level is a dictionary you can use <code>defaultdict(dict)</code> too.		:NOTE: For 2 levels, and 2nd level is a dictionary you can use <code>defaultdict(dict)</code> too.


	==itertools==		==itertools==

2025-12-09T15:37:27Z

sys

← Older revision		Revision as of 15:37, 9 December 2025
Line 50:		Line 50:

	;sys.argv		;sys.argv
	:[[Python:DataTypes#list\|List]] of everything on the commandline. sys.argv[0] is the program itself.		:[[Python:DataTypes#list\|List]] of everything on the commandline. sys.argv[0] is the program itself. All elements of sys.argv are strings.

	;sys.version		;sys.version

2025-08-10T11:41:11Z

← Older revision		Revision as of 11:41, 10 August 2025
Line 237:		Line 237:

	;apt install python3-virtualenv		;apt install python3-virtualenv
	:Install the ~~virtualenvironment~~ script, a nice wrapper for creating ~~vertual~~ environments		:Install the virtualenv script, a nice wrapper for creating virtual environments
	;virtualenv --clear --always-copy -p <~~pythonbinary~~> .venv		;virtualenv --clear --always-copy -p <python binary> .venv
	:Create a virtual environment in the current directory. Clear the existing virtual environment, copy the <pythonbinary> instead of creating a symbolic link.		:Create a fresh virtual environment in the current directory. Clear the existing virtual environment, copy the <pythonbinary> instead of creating a symbolic link.
	This works too, can probably do the same as virtualenv but I haven't ~~checkedmatch~~ of it.		This works too, can probably do the same as virtualenv but I haven't checked much of it.
	;apt install python3.11-venv		;apt install python3.11-venv
	:Install the virtual environment package		:Install the virtual environment package
	;python -m venv .venv		;python -m venv .venv
	:Install the virtual environment in ./.venv with symbolic links to the python binary.		:Install the virtual environment in ./.venv with symbolic links to the python binary.


	;source .venv/bin/activate		;source .venv/bin/activate

2025-07-30T07:03:50Z

traceback

← Older revision		Revision as of 07:03, 30 July 2025
Line 186:		Line 186:

	Module to show where things go wrong. Can be used in [[Python:Control_structures#Exception_handling\|exception handling]]		Module to show where things go wrong. Can be used in [[Python:Control_structures#Exception_handling\|exception handling]]
	~~<syntaxhighlight lang=python>~~
	~~import traceback~~
	~~tracetext = traceback.format_exc() # Return info as string~~
	~~traceback.print_exc() # Print the info~~
	~~</syntaxhighlight>~~

	==bisect==		==bisect==

2025-07-14T10:22:16Z

Virtual environment

← Older revision		Revision as of 10:22, 14 July 2025
Line 241:		Line 241:
	=Virtual environment=		=Virtual environment=

			;apt install python3-virtualenv
			:Install the virtualenvironment script, a nice wrapper for creating vertual environments
			;virtualenv --clear --always-copy -p <pythonbinary> .venv
			:Create a virtual environment in the current directory. Clear the existing virtual environment, copy the <pythonbinary> instead of creating a symbolic link.
			This works too, can probably do the same as virtualenv but I haven't checkedmatch of it.
	;apt install python3.11-venv		;apt install python3.11-venv
	:Install the virtual environment package		:Install the virtual environment package
			;python -m venv .venv
			:Install the virtual environment in ./.venv with symbolic links to the python binary.

	~~;virtualenv --clear --always-copy -p <pythonbinary> .venv~~
	~~:Create a virtual environment in the current directory. Clear the existing virtual environment, copy the files instead of symlinking them and install the <pythonbinary> in it.~~
	~~;python -m venv .venv~~
	~~:This works too, it installs the virtual environment in ./.venv~~

	;source .venv/bin/activate		;source .venv/bin/activate

2025-07-11T09:15:05Z

Virtual environment

@@ Line 240: / Line 240: @@
 =Virtual environment=
 ;virtualenv --clear --always-copy -p <pythonbinary> venv
 :Create a virtual environment in the current directory. Clear the existing virtual environment, copy the files instead of symlinking them and install the <pythonbinary> in it.

2025-07-08T13:31:15Z

traceback

@@ Line 190: / Line 190: @@
 tracetext = traceback.format_exc()   # Return info as string
 traceback.print_exc()  # Print the info
 </syntaxhighlight>

2025-05-20T12:53:44Z

shutil

← Older revision		Revision as of 12:53, 20 May 2025
Line 69:		Line 69:

	==shutil==		==shutil==
			Add shell things to python see [[Python:Files#Filehandling_and_metadata]] for examples for file handling.

	~~;shutil.copy(source, destination)~~
	:~~Copy file from source to destination, destination can be both a~~ file ~~or a directory~~

	~~;shutil~~.~~copyfile(source, destination)~~
	~~:Copy file from source to destination, both as full path~~

	==time==		==time==

2025-04-17T07:33:47Z

itertools

← Older revision		Revision as of 07:33, 17 April 2025
Line 185:		Line 185:

	Module to create various iterators. See the [[Python:DataTypes#Range\|ranges]] section for the count function to create infinite ranges of integers.		Module to create various iterators. See the [[Python:DataTypes#Range\|ranges]] section for the count function to create infinite ranges of integers.


			==traceback==

			See [https://docs.python.org/3/library/traceback.html pythondocs]

			Module to show where things go wrong. Can be used in [[Python:Control_structures#Exception_handling\|exception handling]]
			<syntaxhighlight lang=python>
			import traceback
			tracetext = traceback.format_exc() # Return info as string
			traceback.print_exc() # Print the info
			</syntaxhighlight>

	=Variables=		=Variables=