Python Keywords
and A logical
operator
x = (5
> 3 and
5 < 10)
print(x)
if 5
> 3 and
5 < 10:
print("Both
statements are True")
else:
print("At least one
of the statements are False")
True
Both statements are
True
as To create an
alias
import
calendar as c
print(c.month_name[1])
January
assert For
debugging
x = "hello"
#if condition returns True, then
nothing happens:
assert
x == "hello"
#if condition returns False,
AssertionError is raised:
assert
x == "goodbye",
"x should be 'hello'"
Traceback (most
recent call last):
File "main.py", line 6, in
assert x == "goodbye", "x
should be 'hello'"
AssertionError: x
should be 'hello'
break To break
out of a loop
for i in
range(9):
if i > 3:
break
print(i)
0
1
2
3
i = 1
while i < 9:
print(i)
if i == 3:
break
i += 1
1
2
3
class To define a
class
class Person:
name = "John"
age = 36
p1 = Person()
print(p1.name)
John
continue To
continue to the next iteration of a loop
for i in
range(9):
if i == 3:
continue
print(i)
0
1
2
4
5
6
7
8
i = 0
while i < 9:
i += 1
if i == 3:
continue
print(i)
1
2
4
5
6
7
8
9
def To define a
function
def my_function():
print("Hello from a
function")
my_function()
Hello
from a function
del
To delete an object
class MyClass:
name = "John"
del myClass
print(myClass)
Traceback (most recent call last):
File "main.py", line 3, in
del myClass
NameError: name 'myClass' is not
defined
x = "hello"
del x
print(x)
Traceback (most recent call last):
File "main.py", line 3, in
print(x)
NameError: name 'x' is not defined
x = ["apple",
"banana",
"cherry"]
del x[0]
print(x)
['banana',
'cherry']
elif
Used in conditional statements, same as else if
for i in
range(-5,
5):
if i > 0:
print("YES")
elif i == 0:
print("WHATEVER")
else:
print("NO")
NO
NO
NO
NO
NO
WHATEVER
YES
YES
YES
YES
else
Used in conditional statements
x = 2
if x > 3:
print("YES")
else:
print("NO")
NO
x = 5
try:
x > 10
except:
print("Something
went wrong")
else:
print("The 'Try'
code was executed without raising any errors!")
The
'Try' code was executed without raising any errors!
except
Used with exceptions, what to do when an exception
occurs
try:
x > 3
except:
print("Something
went wrong")
Something went wrong
x = "hello"
try:
x > 3
except
NameError:
print("You have a
variable that is not defined.")
except
TypeError:
print("You are
comparing values of different type")
You are comparing values of different
type
try:
x = 1/0
except
NameError:
print("You have a
variable that is not defined.")
except
TypeError:
print("You are
comparing values of different type")
except:
print("Something
else went wrong")
Something else went wrong
x = 1
try:
x > 10
except
NameError:
print("You have a
variable that is not defined.")
except
TypeError:
print("You are
comparing values of different type")
else:
print("The 'Try'
code was executed without raising any errors!")
The 'Try' code was executed without
raising any errors!
False
Boolean value, result of comparison operations
print(5
> 6)
print(4
in [1,2,3])
print("hello"
is "goodbye")
print(5
== 6)
print(5
== 6 or
6 == 7)
print(5
== 6 and
6 == 7)
print("hello"
is not "hello")
print(not(5
== 5))
print(3
not in [1,2,3])
False
False
False
False
False
False
False
False
False
finally
Used with exceptions, a block of code that will be executed no matter if there
is an exception or not
try:
x > 3
except:
print("Something
went wrong")
else:
print("Nothing went
wrong")
finally:
print("The
try...except block is finished")
Something went wrong
The try...except block is finished
for
To create a for loop
for x in
range(1,
9):
print(x)
1
2
3
4
5
6
7
8
fruits = ["apple",
"banana",
"cherry"]
for x in
fruits:
print(x)
apple
banana
cherry
from
To import specific parts of a module
from datetime import
time
x = time(hour=15)
print(x)
15:00:00
global
To declare a global variable
def myfunction():
global x
x = "hello"
#execute the function:
myfunction()
#x should now be global, and accessible
in the global scope.
print(x)
hello
if make a conditional statement
x = 5
if x > 3:
print("YES")
YES
x = 5
if x > 6:
print("YES")
else:
print("NO")
NO
import To import
a module
import
datetime
x = datetime.datetime.now()
print(x)
2019-04-15 20:41:05.252261
in To check if a
value is present in a list, tuple, etc.
fruits = ["apple",
"banana",
"cherry"]
if "banana"
in fruits:
print("yes")
yes
fruits = ["apple",
"banana",
"cherry"]
for x in
fruits:
print(x)
apple
banana
cherry
is To test if two
variables are equal
x = ["apple",
"banana",
"cherry"]
y = x
print(x is
y)
True
x = ["apple",
"banana",
"cherry"]
y = ["apple",
"banana",
"cherry"]
print(x is
y)
False
lambda To create
an anonymous function
x = lambda
a : a + 10
print(x(5))
15
x = lambda
a, b, c : a + b + c
print(x(5,
6, 2))
13
None Represents a
null value
x = None
print(x)
x = None
if x:
print("Do you think
None is True")
else:
print("None is not
True...")
None
None is not True...
nonlocal To
declare a non-local variable
def myfunc1():
x = "John"
def myfunc2():
x = "hello"
myfunc2()
return x
print(myfunc1())
John
not A logical
operator
x = False
print(not
x)
True
or A logical
operator
x = (5
> 3 or
5 > 10)
print(x)
if 5
> 3 or
5 > 10:
print("At least one
of the statements are True")
else:
print("None of the
statements are True")
True
At least one of the statements are True
pass A null
statement, a statement that will do nothing
class Person:
pass
raise To raise an
exception
x = -1
if x < 0:
raise Exception("Sorry,
no numbers below zero")
Traceback (most recent call last):
File "main.py",
line 3, in
raise
Exception("Sorry, no numbers below zero")
Exception: Sorry, no numbers below zero
x = "hello"
if not
type(x) is
int:
raise TypeError("Only
integers are allowed")
Traceback (most recent call last):
File
"main.py", line 4, in
raise
TypeError("Only integers are allowed")
TypeError: Only integers are allowed
return To exit a
function and return a value
def myfunction():
return 3+3
print(myfunction())
6
def myfunction():
return 3+3
print("Hello,
World!")
print(myfunction())
6
True Boolean
value, result of comparison operations
print(5
< 6)
print(2
in [1,2,3])
print(5
is 5)
print(5
== 5)
print(5
== 5 or
6 == 7)
print(5
== 5 and
7 == 7)
print("hello"
is not "goodbye")
print(not(5
== 7))
print(4
not in [1,2,3])
True
True
True
True
True
True
True
True
True
try To make a
try...except statement
try:
x > 3
except:
print("Something
went wrong")
Something went wrong
try:
x > 3
except:
Exception("Something went wrong")
while To create a
while loop
x = 0
while x < 9:
print(x)
x = x + 1
0
1
2
3
4
5
6
7
8
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