My Python Cheat Sheet

Strings

x = 'a'
x.isalpha()
>>> True
x.isdigit()
>>> False

eval( ' 1*2+3 ' )
>>> 5

ord()
>>>ord('a') 97 >>> ord('b') 98 >>> ord('c') 99


Turn string to lower/upper case
s.lower()
s.upper()
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Numbers

import sys
sys.maxsize # get a large number
-sys.maxsize - 1

cmp(a, b)
-1 if a<b
0 if a=b
1 if a>b

sort by x[0] then by x[1]
temp = sorted(temp, key = lambda x: (x[0], x[1]))

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Lists

sorted(list)
list.sort()

reversed(list)
list.reverse()
list[::-1]

find()
>>> str1 = "this is string example....wow!!!";
>>> str1.find('tri')
9

Counter()
tasks = [A, A, A, B, B, B, B]
d = collections.Counter(tasks)
print(d)
>>> Counter({'A': 3, 'B': 4})

counts = d.values()
print(counts)
>>> dict_values([3, 4])


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Deque
import collections

de = collections.deque([1,2,3])
de.append(4)
de.appendleft(4)
de.pop()
de.popleft()

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Random Library
random.randint(min, max)

pick a random element from a list:
random.choice(list)

pick a random element from a set:
random.sample(set, 1)[0]
random.choice(list(set))

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Binary to decimal
A = int(a, 2)

Decimal to binary
bin(A)