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python

Editor

  1. editor: VSCodium

  2. ipython and ipython notebook

  3. build-ins

    • name
    • doc : documentation in beginning of document """some doc here"""

  4. setup.py building the project to restructure the whole project.

  5. install tree

  6. install anaconda (with python)

codewith.mu - online editor for python for beginners. pygame.org - online til at lave spil.

  1. http.server start og se alle filer i mappen.
  2. library numpy
  3. django for

Collections

List, Tuple, Dictionary

Comprehensions

capitalsDict = {"paris":"France", "London":"England","Lisbon":"Portugal"} reverseKeyValueDict = {capitalsDict[key]:key for key in capitalsDict} //Will return {"France":"Paris",...etc..}

NamedTupple

  • Named tuple is used to find value by a name instead of a numeric index.
  • Person = collections.namedtuple('Person', 'name age gender') and bob = Person(name='Bob', age=30, gender='male')

Anaconda

  • Create a virtual environment for installs: conda create -n exercises and source activate exercises to start up the environment.
  • When conda environment is running -> install module: conda install -c conda-forge pyperclip conda-forge was necesary. conda-forge is a conda repository with many packages to install.

Comments

And documentation.

  • Documentation: first line in function or class or module is written as documentation string with triple quotes: """bla bla bla """ (tripple quotes is used for multiline string).

Idioms (best practises)

https://en.wikibooks.org/wiki/Python_Programming/Idioms

Regexp

ONLINE tester: https://pythex.org/

  • \n backslash is used to escape charaters
  • raw text is text that does not need escaping eg.
    • '\\d\\d\\d-\\d\\d\\d-\\d\\d\\d\\d' vs
    • r'\d\d\d-\d\d\d-\d\d\d\d
  • import re to work with regular expression.
  • phoneNumRegex = re.compile(r'\d\d\d-\d\d\d-\d\d\d\d') phoneNumRegEx is the regex object.
  • search() is a method on the regex object
    • matchFound = phoneNumRegex.search(someString)
    • matchFound.group() matchFound.group() will be the actual phone number that was found.
    • Test a particular pattern on a text online: [http:// regexpal.com/](http:// regexpal.com/)
  • groups() use groups to get a tuple of alle matching strings
  • group(0) all parts of the first match
  • group(1) first part of parenthes match re.compile(r'(\(\d\d\d\)) (\d\d\d-\d\d\d\d)') eg 415 of match 415-333-6545. Notice how \( looks for an actual parenthes.
  • pipe | is used for OR like: re.compile(r'frog|toad') will match either frog or toad and return the first one found.
  • ex: re.compile(r'(frog|toad)leg') to find either frogleg og toadleg.
  • findall() instead of search() will find all occurences.
  • re.compile(r'Bat(wo)?man') a question mark here means 'wo' is optional
  • phoneRegex = re.compile(r'(\d\d\d-)?\d\d\d-\d\d\d\d') the first 3 digits are optional.
  • (\d)* zero or more times with a digit when postfixing an asterix.
  • (\d)+ one or more times when postfixing a plus.
  • (\d){3} only match 3 digits exactly
  • (hi ){3,5} matches 'hi hi hi' and 'hi hi hi hi' and 'hi hi hi hi hi'
  • (hi ){3,5}? with a question mark we get the shortest possible match rather than the default longest match. 'hi hi hi' rather than 'hi hi hi hi hi'.
short hand character description
\d Any numeric digit from 0 to 9.
\D Any character that is not a numeric digit from 0 to 9.
\w Any letter, numeric digit, or the underscore character. (Think of this as matching “word” characters.)
\W Any character that is not a letter, numeric digit, or the underscore character.
\s Any space, tab, or newline character. (Think of this as matching “space” characters.)
\S Any character that is not a space, tab, or newline
  • use ^ caret symbol to match only the start of the string: r'^Hello' will mathc 'Hello you' but not 'Say Hello from Me'.
  • use $ to match the end of the string
  • user ^ and $ to match string exactly: wholeStringIsNum = re.compile(r'^\d+$').
  • use wildcart . to match any charactor that is not a new line.
atRegex = re.compile(r'.at')
atRegex.findall('The cat in the hat sat on the flat mat.')
['cat', 'hat', 'sat', 'lat', 'mat']

  • Match any and all things: .* dot= any char and star=zero or more of them.

  • re.compile('.*', re.DOTALL) will match new lines as well.

  • IGNORE CASE: re.compile(r'robocop', re.I) or re.IGNORECASE

  • Substitute text.

namesRegex = re.compile(r'Agent \w+')
namesRegex.sub('CENSORED', 'Agent Alice gave the secret documents to Agent Bob.')
'CENSORED gave the secret documents to CENSORED.
  • Making complex rexexp readable:
phoneRegex = re.compile(r'''(
(\d{3}|\(\d{3}\))?             # area code
(\s|-|\.)?                     # separator
\d{3}                          # first 3 digits
(\s|-|\.)                      # separator
\d{4}                          # last 4 digits
(\s*(ext|x|ext.)\s*\d{2,5})?   # extension
)''', re.VERBOSE)
  • Use | pipe character to give more parameters to the compile() function: someRegexValue = re.compile('foo', re.IGNORECASE | re.DOTALL | re.VERBOSE) since compile only accepts one parameter.

Files

Read and write to files and folders.

  • import os
  • os.getcwd() get current working directory
  • os.makedirs('new-dir-name') creates a new directory in cwd
  • os.chdir('existing-dir-name') changes current working directory to the one requested
  • os.path.abspath('.') returns the absolute path of a relative path.
  • os.path.getsize('/home/thomas/desktop/somefile.txt') returns the size of a file
  • ``
  • ``
  • ``