Python is one of the most popular languages at present. It is widely used in data science and machine learning, network development, scripting, automation and so on.
There are two reasons for the popularity:
- Simple, elegant and concise, no nonsense code
- Easy to learn, quick to start, friendly to novices
Next, let's share 30 short python codes and feel how to quickly complete interesting tasks in 30 seconds or less. Welcome to collect, pay attention, like and support!
"How can I know if I'm not hurt by java?" 🤪. There are some principles that you must try in person before you know. For example, what is meant by "life is short, I use Python ~".
1. The list value is unique
Use the set() conversion function to determine whether there are duplicate elements in the list.
def all_unique(lst):
return len(lst) == len(set(lst))
x = [1,1,2,2,3,2,3,4,5,6]
y = [1,2,3,4,5]
print(all_unique(x)) # False
print(all_unique(y)) # True2. Deformation words
Judge whether two strings are anamorphic words. Anamorphic words mean that after rearranging the letters, the two strings can be equal. In essence, each character appears the same number of times.
from collections import Counter
def anagram(first, second):
return Counter(first) == Counter(second)
anagram("abcd3", "3acdb") # True3. Memory view
Check the memory usage of an object:
import sys variable = 30 print(sys.getsizeof(variable)) # 24
4. Byte size
This method returns the length of a string in bytes.
def byte_size(string):
return(len(string.encode('utf-8')))
byte_size('😀') # 4
byte_size('Hello World') # 11 5. Print string N times
The following code quickly prints a string N times without using a loop.
n = 2 s ="Programming" print(s * n) # ProgrammingProgramming
6. Initial capitalization
Simply use the title() method to capitalize the first letter of each word in the string.
s = "programming is awesome" print(s.title()) # Programming Is Awesome
7. List blocking
The following method divides a list into small lists of a specified size.
def chunk(list, size):
return [list[i:i+size] for i in range(0,len(list), size)]
print(chunk([1, 2, 3, 4, 5, 6],2))
# [[1, 2], [3, 4], [5, 6]]
print(chunk([1, 2, 3, 4, 5, 6, 7],2))
# [[1, 2], [3, 4], [5, 6], [7]]8. filter fast filtering
Use the filter() method to filter "false" values (False, None, 0, and "") from the list
def compact(lst):
return list(filter(None, lst))
print(compact([0, 1, False, 2, '', 3, 'a', 's', 34]))
# [ 1, 2, 3, 'a', 's', 34 ]9. Array transpose
Skillfully transpose a two-dimensional array with zip().
array = [['a', 'b'], ['c', 'd'], ['e', 'f']]
transposed = zip(*array)
print(list(transposed))
# [('a', 'c', 'e'), ('b', 'd', 'f')]
array = [['a', 'b', 'c'], ['d', 'e', 'f']]
transposed = zip(*array)
print(list(transposed))
# [('a', 'd'), ('b', 'e'), ('c', 'f')]10. Chain comparison
You can make multiple comparisons with various operators in one line, and the magic method is natural.
a = 3 print( 2 < a < 8) # True print(1 == a < 2) # False
11. join() link
Use join() to change the string list into a single string, and each element in the list is separated by commas.
hobbies = ["basketball", "football", "swimming"]
print("My hobbies are:") # My hobbies are:
print(", ".join(hobbies)) # basketball, football, swimming12. Get vowels
The following code gets the vowel ('a ',' e ',' I ',' o ',' U ') letters in the string.
def get_vowels(string):
return [each for each in string if each in 'aeiou']
get_vowels('foobar') # ['o', 'o', 'a']
get_vowels('gym') # []13. De initialisation
Turns the first letter of the string to lowercase.
def decapitalize(str):
return str[:1].lower() + str[1:]
decapitalize('FooBar') # 'fooBar'
decapitalize('FooBar') # 'fooBar'14. Flat list
The following method uses recursion to flatten a potential 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(xs):
flat_list = []
[flat_list.extend(deep_flatten(x)) for x in xs] if isinstance(xs, list) else flat_list.append(xs)
return flat_list
print(deep_flatten([1, [2], [[3], 4], 5]))
# [1,2,3,4,5]15. List difference
The following method simulates a set of lists to quickly calculate the difference.
def difference(a, b):
set_a = set(a)
set_b = set(b)
comparison = set_a.difference(set_b)
return list(comparison)
difference([1,2,3], [1,2,4]) # [3]16. Difference function
The following method returns the difference between the two lists after applying the given function to each element of the 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 } ]17. Chain function
You can call multiple functions on 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)) # 9 18. Duplicate value
Use the feature that set() only contains unique elements to judge whether the list has duplicate values.
def has_duplicates(lst):
return len(lst) != len(set(lst))
x = [1,2,3,4,5,5]
y = [1,2,3,4,5]
print(has_duplicates(x)) # True
print(has_duplicates(y)) # False19. Merge Dictionaries
The following method uses update() to merge the two dictionaries.
def merge_two_dicts(a, b):
c = a.copy() # make a copy of a
c.update(b) # modify keys and values of a with the ones from b
return c
a = { 'x': 1, 'y': 2}
b = { 'y': 3, 'z': 4}
print(merge_two_dicts(a, b)) # {'y': 3, 'x': 1, 'z': 4}In Python 3.5 and above, you can be more elegant:
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}20. Turn two lists into Dictionaries
The following method uses the zip() and dict() functions to convert the two lists into a dictionary.
def to_dictionary(keys, values):
return dict(zip(keys, values))
keys = ["a", "b", "c"]
values = [2, 3, 4]
print(to_dictionary(keys, values)) # {'a': 2, 'c': 4, 'b': 3}21. Skillfully use enumerate
Use enumerate() to get the value and index of the list.
list = ["a", "b", "c", "d"]
for index, element in enumerate(list):
print("Value", element, "Index ", index, )
# ('Value', 'a', 'Index ', 0)
# ('Value', 'b', 'Index ', 1)
#('Value', 'c', 'Index ', 2)
# ('Value', 'd', 'Index ', 3) 22. Time consuming statistics
Use time.time() to calculate the time required to execute a piece of code.
import time
start_time = time.time()
a = 1
b = 2
c = a + b
print(c) #3
end_time = time.time()
total_time = end_time - start_time
print("Time: ", total_time)
# ('Time: ', 1.1205673217773438e-05)23. try-else
else clause is a part of the try/except block. If no exception is thrown, the clause is executed.
try:
2*3
except TypeError:
print("An exception was raised")
else:
print("Thank God, no exceptions were raised.")
#Thank God, no exceptions were raised.24. High frequency discovery
The following method returns the most frequent element in the list.
def most_frequent(list):
return max(set(list), key = list.count)
numbers = [1,2,1,2,3,2,1,4,2]
print(most_frequent(numbers))
# 2
25. Palindrome judgment
Checks whether the given string is a palindrome.
def palindrome(a):
return a == a[::-1]
print(palindrome('mom')) # True
print(palindrome('pythontip')) # False26. Simple calculator
Write a simple calculator without using the if else condition.
import operator
action = {
"+": operator.add,
"-": operator.sub,
"/": operator.truediv,
"*": operator.mul,
"**": pow
}
print(action['-'](50, 25)) # 2527. Random shuffle
Randomize the order of elements in a list with random.shuffle(). Note that shuffle works in place and returns None.
from random import shuffle foo = [1, 2, 3, 4] shuffle(foo) print(foo) # [1, 4, 3, 2] , foo = [1, 2, 3, 4]
28. List expansion
Similar to []. concat(...arr) in JavaScript, flatten a list. Note that the following code cannot flatten deeply nested lists.
def spread(arg):
ret = []
for i in arg:
if isinstance(i, list):
ret.extend(i)
else:
ret.append(i)
return ret
print(spread([1,2,3,[4,5,6],[7],8,9]))
# [1,2,3,4,5,6,7,8,9]
print(spread([1,2,3,[4,5,6],[7],8,9,[10,[11]]]))
# [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, [11]]29. Variable exchange
A very fast way to exchange two variables without using additional variables.
a, b = -1, 14 a, b = b, a print(a) # 14 print(b) # -1
30. Dictionary default
Use dict.get(key,default) to return the default value when the key to be found does not exist in the dictionary.
d = {'a': 1, 'b': 2}
print(d.get('a', 3)) # 1
print(d.get('c', 3)) # 3Section
The 30 interesting python codes shared above hope to be useful to you.
If you think it's OK, praise the collection, and a good man will live a safe life.
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