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Python 3 Beginner's Reference Cheat Sheet by

Python 3 Beginner's reference

Operators

Assignment
 
=
Arithmetic
 
+
, 
-
, 
*
, 
/
, 
%
Comparison
 
>
, 
>=
, 
<
, 
<=
, 
==
, 
!=
Logical
 
not, and, or

String operations (string s)

s.coun­t(s­ubs­tring)
Count occurences
 
s.find­(su­bst­ring)
Index of first occurence
 
s.join­(se­quence)
Concat­enate sequence
 
s.spli­t([­del­imi­ter])
Split into list

List operations (list l, element e)

l.appe­nd(e)
Add e
 
l.remo­ve(e)
Remove e
 
l.pop(e)
Remove and return e
 
l.count(e)
Count occurences
 
l.reve­rse()
Reverse l
 
l.sort()
Sort l

Dictionary operations (dict d, key k)

d.clear()
Clear d
 
d.get(k)
Return d[k]
 
d.keys()
Return keys in d
 
d.values()
Return values in d
 
d.items()
Return key-value pairs in d
 

File operations (file f)

f = open(path)
Open f
 
f.read()
Read f
 
f.read­line()
Read line from f
 
f.read­lines()
Return list of lines in f
 
f.write(s)
Write s to f
 
f.close()
Close f

In-built functions

int()
, 
float()
, 
str()
, 
bool()
...
Type casting
 
len(data)
Length
 
min(va­lues)
, 
max(va­lues)
Minimum / Maximum
 
pow(x,y, [z])
X to the power Y [mod Z]
 
range(­start, stop, [step])
Ordered list
 
input()
, 
print()
Console Input/­Output
 
filter­(fu­nction, array)
Filter array
 
map(fu­nction, array)
Map function onto array
 
id(object)
Unique object ID
 
round(n, [x])
Round n [x decimal places]

Module import

import module
 
from module import submodule
 

Control Flow

if(cond): <co­de> else: <co­de>
If-else
 
if(cond1): <co­de> elif(c­ond1): <co­de> else: <co­de>
If-eli­f-else
 
for i in range(­[st­art], stop, [step]): <co­de>
For loop over range
 
for i in items: <co­de>
For loop over iterable
 
while(­con­dit­ion): <co­de>
While loop
 
break
Exit first enclosing loop
 
continue
Skip to next iteration

Useful standard library modules

math
, 
numpy
, 
scipy
Math
 
matplotlib
Graph plotting
 
random
Random generators
 
datetime
Date and time
 
timeit
Perfor­mance
 
re
Regular expres­sions
 
os
OS intera­ction
 
sys
stdin, stdout, stderr, version
 
urllib
Internet access
 
zlib
Data compre­ssion

Object­-or­iented

class Person:
Class definition
 
x = Person­(age, height)
Object creation
 
x.age
Field access
 
x.birt­hday()
Method access
                   
 

Metadata

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  • Published: 17th December, 2016
  • Rated: 5 out of 5 stars based on 4 ratings

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