| and | A logical operator | >>>x = 2 > 0
>>>x == True
True
|
|
| as | To create an alias | >>> from pprint import pprint as pp
>>> pp("pretty print")
'pretty print'
|
|
| assert | For debugging | >>> assert(10<5)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
AssertionError
|
|
| break | To break out of a loop | >>> i=0
>>> j = 0
>>> for x in range(3,20):
... j = x
... if x % i == 2:
... break
...
>>> j
12
|
|
| class | To define a class | >>> class Circle:
... pi = 3.14
...
>>> print(Circle.pi)
3.14
|
|
| continue | To continue to the next iteration of a loop | >>> i=[]
>>> for x in range(1, 20):
... if x % 2 == 0:
... continue
... i.append(x)
...
>>> i
[1, 3, 5, 7, 9, 11, 13, 15, 17, 19]
|
|
| def | To define a function | >>> def even(n):
... return n%2 == 0
...
>>> even(11)
False
|
|
| del | To delete an object or attribute | >>> x = {'y': 15, 'z':31}
>>> del x['z']
>>> x
{'y': 15}
>>> del x
|
|
| elif | Used in conditional statements, same as else if | >>> def test(n):
... if n>0:
... return '+ve'
... elif n<0:
... return '-ve'
... else:
... return 'zero'
...
>>> test(0)
'zero'
>>> test(-10)
'-ve'
|
|
| else | Used in conditional statements | >>> def test(n):
... if n>0:
... return '+ve'
... elif n<0:
... return '-ve'
... else:
... return 'zero'
...
>>> test(0)
'zero'
|
|
| except | Used with exceptions, what to do when an exception occurs | >>> def divide(x, y):
... try:
... print(x/y)
... except:
... print("Cannot divide")
...
>>> divide(20, 10)
2.0
>>> divide(20, 0)
Cannot divide
|
|
| False | Boolean value, result of comparison operations | | |
| finally | Used with exceptions, after try-except blocks, a block of code to be executed no matter if there is an exception or not | >>> def divide(x, y):
... try:
... print(x/y)
... except:
... print("Cannot divide")
... finally:
... print("Unaffected by exception")
...
>>> divide(20, 10)
2.0
Unaffected by exception
>>> divide(20, 0)
Cannot divide
Unaffected by exception
|
|
| for | To create a for loop | >>> for i in range(0,3):
... print(i * i)
...
0
1
4
|
|
| from | To import specific parts of a module | >>> from math import pi
>>> pi
3.141592653589793
|
|
| global | To declare a global variable | >>> i = 12
>>> def x():
... i = 15
...
>>> def y():
... global i
... i = i + 2
...
>>> x()
>>> i
12
>>> y()
>>> i
14
|
|
| if | To make a conditional statement | >>> def test(n):
... if n>0:
... return '+ve'
... elif n<0:
... return '-ve'
... else:
... return 'zero'
...
>>> test(10)
'+ve'
|
|
| import | To import a module | >>> import math
>>> math.pi
3.141592653589793
|
|
| in | To check if a value is present in a list, tuple, etc | >>> 2 in range(1, 10)
True
>>> 2 in [3,4,5]
False
|
|
| is | To test if two variables are equal | >>> x = 5; y = 5
>>> x is y
True
|
|
| lambda | To create an anonymous function | >>> sq=lambda x: x * x
>>> sq(11)
121
|
|
| None | Represents a null value | >>> x = None
>>> type(x)
<class 'NoneType'>
|
|
| nonlocal | To declare a non-local variable | >>> x = 5; y = 8
>>> def change():
... x = 14
... y = x - 3
... def change2():
... nonlocal y
... y = y * y
... change2()
... print(y)
...
>>> change()
121
|
|
| not | A logical operator | >>>True and False
False
|
|
| or | A logical operator | >>> 6 is not 5
True
|
|
| pass | A null statement, a statement that does nothing, often used as placeholder | >>> def empty_method():
... pass
...
|
|
| raise | To raise an exception | >>> raise RuntimeError
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
RuntimeError
|
|
| return | To exit a function and return a value | >>> def zero():
... return 0
...
>>> zero()
0
|
|
| True | Boolean value, result of comparison operations | | |
| try | To make a try...except statement | >>> def divide(x, y):
... try:
... print(x/y)
... except:
... print("Cannot divide")
...
>>> divide(20, 10)
2.0
>>> divide(20, 0)
Cannot divide
|
|
| while | To create a while loop | >>> i = 0
>>> while i <5:
... print(i * i)
... i+=1
...
0
1
4
9
16
|
|
| with | Used to simplify exception handling, for example when a file is opened by with keyword, then Python handles closing of the file after block is executed and file object goes out of scope | >>> >>> with open('/tmp/testfile', 'wb+') as f:
... read_data = f.read()
...
>>> f.closed
True
|
|
| yield | To end a function, returns a generator | >>> def yielder():
... for i in range(0, 5):
... yield i
...
>>> print(yielder())
<generator object yielder at 0x7f21275eed00>
>>> for x in yielder():
... print(x)
...
0
1
2
3
4
>>> z = list(yielder())
>>> z
[0, 1, 2, 3, 4]
|
|
