String
Trick #1 Reversing String
a=”new”
print(“Reverse is”, a[::-1])
Output: Reverse is wen
Trick #2 Splitting String into multiples
a="Who Are You"b=a.split()print(b)
Output: [‘Who’, ‘Are’, ‘You’]
Trick #3 Printing out multiples of strings
print(“me”*8+’ ‘+”no”*10)
Output: memememememememe nononononononononono
Trick #4 Creating a single string
a = [“I”, “am”, “here”]
print(“ “.join(a))
Output: I am here
Trick #5 Check if two words are anagrams
from collections import Counter
def is_anagram(str1, str2):
return Counter(str1) == Counter(str2)
print(is_anagram(‘geek’, ‘eegk’))
print(is_anagram(‘geek’, ‘peek’))
Output:
True
False
List
Trick #6 Flatten Lists
import itertools
a = [[1, 2], [3, 4], [5, 6]]
b = list(itertools.chain.from_iterable(a))
print(b)
Output: [1, 2, 3, 4, 5, 6]
Trick #7 Reverse a list
a=[“10”,”9",”8",”7"]
print(a[::-1])
Output: [‘7’, ‘8’, ‘9’, ‘10’]
Trick #8 Unpack list in quick loop
a=[“10”,”9",”8",”7"]
for e in a:
print(e)
Output:
10
9
8
7
Trick #9 Combining two lists
a=[‘a’,’b’,’c’,’d’]
b=[‘e’,’f’,’g’,’h’]
for x, y in zip(a, b):
print(x,y)
Output:
a e
b f
c g
d h
Trick #10 Negative Indexing Lists
a = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
a[-3:-1]
Output:
[8, 9]
Trick #11 Check for most frequent on the list
a =[1, 2, 3, 4, 2, 2, 3, 1, 4, 4, 4]
print(max(set(a), key =a.count))
Output:
4
Matrix
Trick #12 Transposing a matrix
mat = [[1, 2, 3], [4, 5, 6]]
new_mat=zip(*mat)
for row in new_mat:
print(row)
Output:
(1, 4)
(2, 5)
(3, 6)
Operators
Trick #13 Chaining comparison operators
a = 5
b = 10
c = 3
print(c < a)
print(a < b)
print(c < a < b)
Output:
True
True
True
Dictionary
Trick #14 Inverting Dictionary
dict1={‘a’: 1, ‘b’: 2, ‘c’: 3, ‘d’: 4}
dict2={v: k for k, v in dict1.items()}
print(dict2)
Output:
{1: ‘a’, 2: ‘b’, 3: ‘c’, 4: ‘d’}
Trick #15 Iterating over dictionary key and value pairs
dict1={‘a’: 1, ‘b’: 2, ‘c’: 3, ‘d’: 4}
for a, b in dict1.iteritems():
print (‘{: {}’.format(a,b))
Output:
a: 1
b: 2
c: 3
d: 4
Trick #16 Merging Dictionaries
x = {'a': 1, 'b': 2}
y = {'b': 3, 'c': 4}
z = {**x, **y}
print(z)
Output:
{‘a’: 1, ‘b’: 3, ‘c’: 4}
Initialization
Trick #17 Initializing empty containers
a_list = list()
a_dict = dict()
a_map = map()
a_set = set()
Trick #18 Initializing List filled with some numbers
#listA contains 1000 0's
listA=[0]*1000
#listB contains 1000 2's
listB=[2]*1000Misc
Trick #19 Check Memory Usage of An Object
import sys
a=10
print(sys.getsizeof(a))
Output: 28
Trick #20 Swapping Values
x, y = 1, 2
x, y = y, x
print(x, y)
Output:
2 1
Source : https://towardsdatascience.com/20-python-programming-tips-and-tricks-for-beginners-25d44db03aea