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The following method can check whether there are duplicates in a given list, and use the set() attribute to delete them from the list.
x = [1,1,2,2,3,2,3,4,5,6] y = [1,2,3,4,5] len(x)== len(set(x)) # False len(y)== len(set(y)) # True
This method can be used to check whether two strings are anagrams.
from collections import Counter
>>> Counter('abadfsdafsdfjsdaf')
Counter({'a': 4, 'd': 4, 'f': 4, 's': 3, 'b': 1, 'j': 1})
def anagram(first, second):
return Counter(first) == Counter(second)
anagram("abcd3", "3acdb") # TrueThis code snippet can be used to check the memory usage of an object.
import sys variable = 30 print(sys.getsizeof(variable)) # 28
This method can output the byte size of the string.
print(len(''.encode('utf-8')))# 0 print(len('hellow sdfsdaf'.encode('utf-8'))) # 14
This code segment can print a string multiple times without looping.
n = 2; s ="Programming"; print(s * n); # ProgrammingProgramming
The following code snippet only uses title() to capitalize the first letter of each word in the string.
s = "programming is awesome" print(s.title()) # Programming Is Awesome
This method subdivides the list into lists of a specific size.
>>> list = list(range(12)) >>> size=3 >>> [list[i:i+size] for i in range(0,len(list), size)] [[0, 1, 2], [3, 4, 5], [6, 7, 8], [9, 10, 11]] >>>
The following code uses filter() to remove error values (False, None, 0 and " ") from the list.
list(filter(bool, [0, 1, False, 2, '', 3, 'a', 's', 34]))
The following code can be used to swap the 2D array arrangement.
array = [['a', 'b'], ['c', 'd'], ['e', 'f']] transposed = zip(*array) print(transposed) # [('a', 'c', 'e'), ('b', 'd', 'f')]
The following code can perform multiple comparisons on various operators.
a = 3 print( 2 < a < 8) # True print(1 == a < 2) # False
This code snippet converts a list of strings into a single string while separating each element in the list with a comma.
hobbies = ["basketball", "football", "swimming"]
print("My hobbies are: " + ", ".join(hobbies)) # My hobbies are: basketball, football, swimmingThis method can count the number of vowels ("a", "e", "i", "o", "u") in the string .
import re print(len(re.findall(r'[aeiou]', 'foobar', re.IGNORECASE))) # 3 print(len(re.findall(r'[aeiou]', 'gym', re.IGNORECASE))) # 0
This method converts the first letter of the given string into lowercase mode.
'FooBar'[:1].lower() + 'FooBar'[1:] # 'fooBar' 'FooBar'[:1].lower() + 'FooBar'[1:] # 'fooBar'
The following code uses a recursive method to expand a potentially deep list.
def spread(arg):
ret = []
for i in arg:
if isinstance(i, list):
ret.extend(i)
else:
ret.append(i)
return ret
def deep_flatten(lst):
result = []
result.extend(
spread(list(map(lambda x: deep_flatten(x) if type(x) == list else x, lst))))
return result
deep_flatten([1, [2], [[3], 4], 5]) # [1,2,3,4,5]
print(deep_flatten([1, [2], [[3], 4], 5])) # [1,2,3,4,5]This method keeps only the values in the first iteration to find the difference between the two iterations
set([1,2,3])-set([1,2,4]) # [3]
The following method uses existing functions to find and output the difference between two lists.
def difference_by(a, b, fn):
b = set(map(fn, b))
return [item for item in a if fn(item) not in b]
from math import floor
difference_by([2.1, 1.2], [2.3, 3.4],floor) # [1.2]
difference_by([{ 'x': 2 }, { 'x': 1 }], [{ 'x': 1 }], lambda v : v['x']) # [ { x: 2 } ]The following method can call multiple functions in one line
def add(a, b):
return a + b
def subtract(a, b):
return a – b
a, b = 4, 5
print((subtract if a > b else add)(a, b)) # 9In Python3.5 and In the upgraded version, you can also execute the step code in the following way:
def merge_dictionaries(a, b):
return {**a, **b}
a = { 'x': 1, 'y': 2}
b = { 'y': 3, 'z': 4}
print(merge_dictionaries(a, b)) # {'y': 3, 'x': 1, 'z': 4}The following method can convert two lists into fonts.
keys = ["a", "b", "c"]
values = [2, 3, 4]
print(dict(zip(keys, values))) # {'a': 2, 'c': 4, 'b': 3}This method will output the element with the highest frequency of appearance in the list.
def most_frequent(list):
return max(set(list), key = list.count)
list = [1,2,1,2,3,2,1,4,2]
most_frequent(list)The following code checks whether the given string is a palindrome. First convert the string to lowercase, then remove non-alphabetic characters from it, and finally compare the new string version to the original version.
def palindrome(string):
from re import sub
s = sub('[\W_]', '', string.lower())
return s == s[::-1]
palindrome('taco cat') # TrueThe following code snippet shows how to write a simple calculator without if-else conditional statements.
import operator
action = {
"+": operator.add,
"-": operator.sub,
"/": operator.truediv,
"*": operator.mul,
"**": pow
}
print(action['-'](50, 25)) # 25This algorithm uses the Fisher-Yates algorithm to randomly sort the elements in the new list.
from copy import deepcopy
from random import randint
def shuffle(lst):
temp_lst = deepcopy(lst)
m = len(temp_lst)
while (m):
m -= 1
i = randint(0, m)
temp_lst[m], temp_lst[i] = temp_lst[i], temp_lst[m]
return temp_lst
foo = [1, 2, 3]
shuffle(foo) # [2,3,1] , foo = [1,2,3]This method can only expand 2 levels of nested lists, not more than 2 levels
def spread(arg):
ret = []
for i in arg:
if isinstance(i, list):
ret.extend(i)
else:
ret.append(i)
return ret
spread([1, 2, 3, [4, 5, 6], [7], 8, 9]) # [1,2,3,4,5,6,7,8,9]
print(spread([1, 2, 3, [4, 5,[10,11,12,132,4,[1,2,3,4,5,6]], 6], [7], 8, 9])) #[1, 2, 3, 4, 5, [10, 11, 12, 132, 4, [1, 2, 3, 4, 5, 6]], 6, 7, 8, 9]The above is the detailed content of What are some very practical Python skills?. For more information, please follow other related articles on the PHP Chinese website!