Python Crash Course

Lists and sets



In [2]:

    
# Regarding lists in python
my_list = ['a', 'b', 'c', 'd']



In [3]:

    
print(my_list[0:2])    # grab everything from index 0 uptill index 2 but not including index 2









    



['a', 'b']



In [4]:

    
print(my_list[:2])     # grab everything from everythin uptill index 2 but not including index 2









    



['a', 'b']



In [5]:

    
print([my_list[2:]])   # grab everything from index 2 uptill everything









    



[['c', 'd']]



In [7]:

    
# Nested lists
nested = [1,2,['a','b']]



In [8]:

    
print(nested[2][0])



In [9]:

    
# Regarding sets
# Sets are the collection on unique items 
s = {1,2,3,5,5,5,5,1,6}
print(s)









    



{1, 2, 3, 5, 6}



In [10]:

    
# Or
s = set([1,1,1,6,3,3,8,4])
print(s)









    



{1, 3, 4, 6, 8}



In [11]:

    
1 == 1









    Out[11]:





True



In [12]:

    
1 > 2









    Out[12]:





False



In [13]:

    
1 < 6









    Out[13]:





True



In [14]:

    
3 >= 3









    Out[14]:





True



In [16]:

    
1 == '1'     #important









    Out[16]:





False



In [17]:

    
(1 == 1) and (1 == 2)









    Out[17]:





False



In [18]:

    
(1 == 1) or (1 == 2)









    Out[18]:





True



In [19]:

    
(1 == 1) and not (1 == 2)









    Out[19]:





True



In [20]:

    
if True:
    print('hello')









    



hello



In [21]:

    
if False:
    print('hello')
elif True:
    print('elif is True')









    



elif is True



In [22]:

    
if False:
    print('hello')
elif False:
    print('elif is True')
else:
    print('else is True')









    



else is True



In [23]:

    
def power_2(num):
    return num ** 2



In [24]:

    
power_2(4)









    Out[24]:





16



In [25]:

    
seq = [1,2,3,4,5,6,7,8,9]
list(map(lambda num: num ** 2, seq))









    Out[25]:





[1, 4, 9, 16, 25, 36, 49, 64, 81]



In [26]:

    
def is_even(num):
    return num % 2 == 0

list(filter(is_even, seq))









    Out[26]:





[2, 4, 6, 8]



In [27]:

    
list(filter(lambda num: num % 2 == 0, seq))









    Out[27]:





[2, 4, 6, 8]



In [28]:

    
lst = [1,2,3]



In [29]:

    
'x' in [1,2,3]









    Out[29]:





False



In [30]:

    
'x' in ['x','y','z']









    Out[30]:





True



In [ ]: