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* [[Python]] | * [[Python]] | ||
* [[Python/Pythonic Concepts]] | |||
* [[Python/Object Orientation]] | * [[Python/Object Orientation]] | ||
* [[Python/decorators]] | * [[Python/decorators]] | ||
* [[Python/Jupyter | * [[Python/Jupyter]] | ||
* [[Python/Jupyter Installation]] | |||
* [[Python/pip]] | |||
* [[Python/requirements.txt]] | |||
* [[Python/venv]] | |||
* [[Python/Best Practices]] | |||
* [[Python/REST]] | |||
|- | |||
| Libraries | |||
|- | |||
| | |||
* [[Python/logging]] | |||
* [[Python/requests]] | |||
* [[Python/selenium]] | |||
* [[Python/flask]] | * [[Python/flask]] | ||
* [[Python/pandas]] | |||
* [[Python/bokeh]] | * [[Python/bokeh]] | ||
* [[Python/beautifulsoup]] | * [[Python/beautifulsoup]] | ||
* [[Python/pymysql]] | * [[Python/pymysql]] | ||
* [[Python/SQLite]] | * [[Python/SQLite]] | ||
* [[Python/ | * [[Python/feedparser]] | ||
* [[Python/ | * [[Python/Desktop Automation]] | ||
* [[Python/ | * [[Python/traceback]] | ||
|} | |} | ||
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</blockquote> | </blockquote> | ||
* | * [[#sorted()]] | ||
== List Comprehension == | |||
<blockquote> | <blockquote> | ||
<pre> | <pre> | ||
[expression for item in list (if condition)] | [expression for item in list (if condition)] | ||
[x*5 for x in range(5)] | [x*5 for x in range(5)] -> [0, 5, 10, 15, 20] | ||
[x for x in range(5) if x%2 == 0] | [x for x in range(5) if x%2 == 0] -> [0, 2, 4] | ||
[i*i for i in range(5)] | [i*i for i in range(5)] -> [0, 1, 4, 9, 16] | ||
</pre> | |||
</blockquote> | |||
<blockquote> | |||
<pre> | |||
[ x for x in books if (x['language'] == "de"] # filter | |||
</pre> | </pre> | ||
</blockquote> | </blockquote> | ||
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<blockquote> | <blockquote> | ||
<pre> | <pre> | ||
+ | ##### arithmetic operators ##### | ||
- | + addition | ||
* | - subtraction | ||
/ | * multiplication | ||
/ division | |||
% | % modulus | ||
** | ** exponentiation | ||
// floor division | |||
##### comparison operators ##### | |||
== equal | |||
!= not equal | |||
< less than | |||
<= less than or equal to | |||
> greater than | |||
>= greater than or equal to | |||
is | is | ||
is not | is not | ||
in | in | ||
not in | not in | ||
and | and | ||
or | or | ||
not | |||
##### bitwise operators ##### | |||
& and | |||
| or | |||
^ xor | |||
~ not | |||
<< | |||
>> | |||
</pre> | </pre> | ||
</blockquote> | </blockquote> | ||
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string = "Hello World" | string = "Hello World" | ||
string = 'Hello World' | string = 'Hello World' | ||
string | string = '''multiline | ||
string''' | |||
string[4] # = 'o' | string[4] # = 'o' | ||
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ljust(width) | ljust(width) | ||
lower() | lower() | ||
partition(sep) | partition(sep) | ||
replace(old,new) | replace(old,new) # replace old string with new string | ||
replace(" ","") # remove all spaces | |||
rfind(sub,start,end) | rfind(sub,start,end) | ||
rindex(sub,start,end) | rindex(sub,start,end) | ||
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rpartition(sep) | rpartition(sep) | ||
rsplit(sep) | rsplit(sep) | ||
split(sep) | split(sep) | ||
splitlines() | splitlines() | ||
startswith(sub) | startswith(sub) | ||
strip() | strip() #remove leading and trailing whitespaces | ||
rstrip() | |||
lstrip() | |||
swapcase() | swapcase() | ||
title() | title() | ||
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upper() | upper() | ||
zfill(width) | zfill(width) | ||
''.join(e for e in string if e.isalnum()) # remove all special chars in string | |||
</pre> | </pre> | ||
</blockquote> | </blockquote> | ||
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= Functions = | = Functions = | ||
== | == User Defined Functions == | ||
<blockquote> | <blockquote> | ||
<pre> | <pre> | ||
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userfunction(1,2,3,4) | userfunction(1,2,3,4) | ||
</pre> | |||
</blockquote> | |||
== Lambda == | |||
small function, with any number of arguments | |||
<blockquote> | |||
<pre> | |||
x = lambda a : a + 10 | |||
print(x(5)) | |||
x = lambda a, b : a * b | |||
print(x(5, 6)) | |||
(lambda x, y: x + y)(2, 3) | |||
5 | |||
</pre> | </pre> | ||
</blockquote> | </blockquote> | ||
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with ignored(OSError): | with ignored(OSError): | ||
os.remove('somefile.tmp') | os.remove('somefile.tmp') | ||
</pre> | |||
</blockquote> | |||
== sorted() == | |||
<blockquote> | |||
<pre> | |||
sorted([5, 2, 3, 1, 4]) -> [1, 2, 3, 4, 5] | |||
sorted("This is a test string".split(), key=str.lower) -> ['a', 'is', 'string', 'test', 'This'] | |||
user_tuples = [('john', 15),('jane', 12),('dave', 10)] | |||
sorted(user_tuples, key=lambda user: user[1]) -> [('dave', 10), ('jane', 12), ('john', 15)] | |||
books_sorted = sorted(books_with_review, key=lambda k: k['amz-num'], reverse=True) | |||
</pre> | </pre> | ||
</blockquote> | </blockquote> | ||
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</pre> | </pre> | ||
</blockquote> | </blockquote> | ||
[[Category:Programming]] |
Latest revision as of 15:13, 28 September 2024
Other articles |
Libraries |
Python Shebang
#!/usr/bin/env python3
Comments
# This is a comment print("Hello, World!")
Variables
Tuples
- not changeable
a = (1,2,3) b = ("test", "with", "strings")
b[0] -> test
Lists
- changeable
c = [4,5,6] d = ["this", "is", "a", "list"]
d[0] -> 'this'
d[0] = 'this' d[0:1] = ['this', 'is'] d[0:-1] = ['this', 'is', 'a'] d.index(x) # Return index of the first item whose value is x len(d) # length 'term' in d # find d.count('new') # count number of 'new' d.append('dude') # add item to list d.extend(['more', 'elements'] # Extend the list by appending all the items from the iterable d.insert(i,x) # Insert an item at a given position del d[0:1] # remove item at given index d.remove(x) # Remove the first item from the list whose value is x d.pop() # Remove the item at the given position in the list d.clear() # remove all items d.reverse() # reverse elements in place d.sort(key=None, reverse=False) # sort the items of the list
List Comprehension
[expression for item in list (if condition)] [x*5 for x in range(5)] -> [0, 5, 10, 15, 20] [x for x in range(5) if x%2 == 0] -> [0, 2, 4] [i*i for i in range(5)] -> [0, 1, 4, 9, 16]
[ x for x in books if (x['language'] == "de"] # filter
Dictionaries
- mapping
e = {'size':5, 'color':'red', 'weight':100}
e['size'] -> 5
keys = ['a', 'b', 'c'] values = [1, 2, 3] dictionary = dict(zip(keys, values))
for k, v in e.items(): print (k, v)
e[k] e[k] = x e.clear() e.copy() del e[k] e.get(k,x) k in e k not in e e.items() e.keys() e.popitem() e.setdefault() e1.update(e2) e.values()
import copy
new_dict = copy.deepcopy(old_dict)
Assigning values
x = 1 first, second, third = sequence x, y = 0, 1 x, y = y, x+y x, _, y = (1, 2, 3) y += 1
Operators
##### arithmetic operators ##### + addition - subtraction * multiplication / division % modulus ** exponentiation // floor division ##### comparison operators ##### == equal != not equal < less than <= less than or equal to > greater than >= greater than or equal to is is not in not in and or not ##### bitwise operators ##### & and | or ^ xor ~ not << >>
Flow Control
If Then Else
if x < 0: print('Negative') elif x == 0: print('Zero') else: print('More')
For loops
for x in ['cat', 'dog', 'bird']: print (x)
for i in [1,2,3,4,5]: print (i+10)
for item in container: if search_something(item): print(item) # Found it! break else: not_found_in_container() # Didn't find anything..
for index, element in enumerate(newarticles): print(index, element)
While loops
while test: print (answer)
while True: print (answer) if answer == '2': break
x = 0 while x < 50: x = x+1
try ... except
try: result = x / y except ZeroDivisionError: print("division by zero!") else: print("result is", result) finally: print("executing finally clause")
Statements
assert # for debugging, will raise AssertionError if 'assert [false]' break # break out of for or while loop continue # end current iteration in a for or while loop nonlocal pass # placeholder for future code raise # raise exception return yield
Strings
string = "Hello World" string = 'Hello World' string = '''multiline string''' string[4] # = 'o' string[-1] # = 'd' string[:-7] # = 'Hell' string.split(' ') # ['Hello', 'World']
String functions
capitalize() center(width) count(sub,start,end) decode() encode() endswith(sub) expandtabs() find(sub,start,end) index(sub,start,end) isalnum() isalpha() isdigit() islower() isspace() istitle() isupper() join() ljust(width) lower() partition(sep) replace(old,new) # replace old string with new string replace(" ","") # remove all spaces rfind(sub,start,end) rindex(sub,start,end) rjust(width) rpartition(sep) rsplit(sep) split(sep) splitlines() startswith(sub) strip() #remove leading and trailing whitespaces rstrip() lstrip() swapcase() title() translate(table) upper() zfill(width) ''.join(e for e in string if e.isalnum()) # remove all special chars in string
Input & Output
x = input("input:")
print(x+12) print("Hello world") print("Integer: %i, Float: %6.2f" % (123, 12.043)) print("Integer: {intvar:i}, Float: {floatvar:.2f}") print("value of x: {0:05d}".format(x)) print("%3i%6s" % (i, chr(i)))
import sys sys.argv[0] -> first command line argument
Files
file = open (ordersfile, 'rb') file.read() file.readline() file.readlines() file.close()
import pickle with open(ordersfile, 'wb') as fp: pickle.dump(orders, fp) with open (ordersfile, 'rb') as fp: orders = pickle.load(fp)
import os.path os.path.exists(file_path)
Escape sequences
ES Note \\ backslash \' ' \" " \b backspace \f form feed \n line feed \t horizontal tab \v vertical tab \N{Name} Unicode by name \uxxxx 16bit unicode \uxxxxxxxx 32bit unicode \123 ASCII code \xhh Extended ASCII code (hex)
Double underscore variables
- __file__
- path of script
import os os.path.split(__file__)[0] + '/'
- __name__
- name of submodule or "__main__", if script is directly started
Functions
User Defined Functions
def userfunction(): print("Hello") userfunction()
def userfunction(variable): print("Hello", variable) userfunction('Peter')
def userfunction(variable): print("Hello", variable) test = 2 return test print(userfunction('Peter')) # prints "2"
def userfunction(variable1, variable2 = "John"): print("Hello", variable1, variable2) userfunction("dear")
def userfunction(*variables): for var in variables: print(var) userfunction(1,2,3,4)
Lambda
small function, with any number of arguments
x = lambda a : a + 10 print(x(5)) x = lambda a, b : a * b print(x(5, 6)) (lambda x, y: x + y)(2, 3) 5
import datetime
today() now(timezoneinfo) utcnow() fromordinal(ordinal) combine(date,time) strptime(date,format) fromtimestamp(timestamp) utcfromtimestamp(timestamp)
import time
replace() utcoffset() isoformat() __str__() dst() tzname() strftime(format) sleep()
timeit
from timeit import default_timer as timer start = timer() do_something() end = timer() print(end-start)
strftime & strptime format
%a Weekday as locale’s abbreviated name. Sun, Mon, …, Sat (en_US);So, Mo, …, Sa (de_DE) %A Weekday as locale’s full name. Sunday, Monday, …, Saturday (en_US);Sonntag, Montag, …, Samstag (de_DE) %w Weekday as a decimal number. Sundy=0 0, 1, …, 6 %d Day of the month, zero-padded 01, 02, …, 31 %b Month as locale’s abbreviated name. Jan, Feb, …, Dec (en_US);Jan, Feb, …, Dez (de_DE) %B Month as locale’s full name. January, February, …, December (en_US);Januar, Februar, …, Dezember (de_DE) %m Month as a zero-padded decimal number. 01, 02, …, 12 %y Year without century, zero-padded 00, 01, …, 99 %Y Year with century as a decimal number. 0001, 0002, …, 2013, 2014, …, 9998, 9999 %H Hour (24-hour clock), zero-padded 00, 01, …, 23 %I Hour (12-hour clock), zero-padded 01, 02, …, 12 %p Locale’s equivalent of either AM or PM. AM, PM (en_US);am, pm (de_DE) %M Minute, zero-padded 00, 01, …, 59 %S Second,zero-padded 00, 01, …, 59 %f Microsecond, zero-padded 000000, 000001, …, 999999 %z UTC offset in the form ±HHMM[SS[.ffffff]] (empty), +0000, -0400, +1030, +063415, -030712.345216 %Z Time zone name (empty if none) (empty), UTC, EST, CST %j Day of the year, zero-padded 001, 002, …, 366 %U Week number, Sunday first day of week 00, 01, …, 53 %W Week number, Monday first day of week 00, 01, …, 53 %c Locale’s appropriate date and time Tue Aug 16 21:30:00 1988 (en_US);Di 16 Aug 21:30:00 1988 (de_DE) %x Locale’s appropriate date 08/16/88 (None); 08/16/1988 (en_US); 16.08.1988 (de_DE) %X Locale’s appropriate time 21:30:00 (en_US); 21:30:00 (de_DE) %% A literal '%' character. %
import os
with ignored(OSError): os.remove('somefile.tmp')
sorted()
sorted([5, 2, 3, 1, 4]) -> [1, 2, 3, 4, 5] sorted("This is a test string".split(), key=str.lower) -> ['a', 'is', 'string', 'test', 'This'] user_tuples = [('john', 15),('jane', 12),('dave', 10)] sorted(user_tuples, key=lambda user: user[1]) -> [('dave', 10), ('jane', 12), ('john', 15)] books_sorted = sorted(books_with_review, key=lambda k: k['amz-num'], reverse=True)
other
iter range xrange sorted() sorted,x, reverse=True) reversed()