Jun 01, 2021 Article blog
After learning about
Python
and writing code with it once, I was fascinated by its simplicity, excellent readability, and useful one-line code.
Next, I'll introduce you to a line of code that might be helpful for your
Python
project.
# a = 1; b = 2
a, b = b, a
# print(a,b) >> 2 1Let's start with a classic: by simply exchanging assignment positions to exchange the values of variables -- in my opinion, this is the most intuitive approach. T emporary variables are not required. It even applies to more than two variables.
a, b, *c = [1,2,3,4,5]
# print(a,b,c) >> 1 2 [3, 4, 5]
Swap variables are actually a special case where
python
can allocate multiple variables at once. H
ere, you can use it to assign list elements to a given variable, also known as a de-table.
*
remaining values will be packaged again, which will result in a sublist of
c
It can even be used in other places of
*
(such as the beginning or middle part of the list).
# a = [1,2,3,4,5,6]
s = sum(a[1::2])
# print(s) >> 12
There is no need for a special
reduce
function here,
sum
simply adds items for each given iteration. T
he second element is returned here using the
[::]
slice syntax .
You can read it as
[start: stop: step]
so
[1::2]
translation starts with the element of index 1 (the second element) until the end of the list (the second argument does not give parameters), and always takes two steps.
(Recommended tutorial: python tutorial)
# a = [1,2,3,4,5]
del a[::2]
# print(a) >> [2, 4]Extended tile syntax can also be used to remove multiple list elements at once.
c = [line.strip() for line in open('file.txt')]
# print(c) >> ['test1', 'test2', 'test3', 'test4']
With
python
inline
for
loops, you can easily read files into an array of rows. Y
ou need to use
strip()
to remove the broken line that follows.
If you want to keep them or they don't matter to you, you can use shorter lines:
c = list(open('file.txt'))
# print(c) >> ['test1\n', 'test2\n', 'test3\n', 'test4\n']
Reading files in
Python
is really easy.
Note: You can also use the
readlines()
method if you prefer.
with open('file.txt', 'a') as f: f.write('hello world')
# print(list(open('file.txt'))) >> ['test1\n', 'test2\n', 'test3\n', 'test4\n', 'hello world']
With the help of the
With
statement, you can write content directly to a file.
Make sure to open the file in the correct mode (where "a" means additional content).
l = [('Hi ' + x) for x in ['Alice', 'Bob', 'Pete']]
# print(l) >> ['Hi Alice', 'Hi Bob', 'Hi Pete']
You can use inline for loops
for
dynamically create lists from other lists.
You can modify the values directly, just like string connections in this example.
l = list(map(int, ['1', '2', '3']))
# print(l) >> [1, 2, 3]
You can also use
Pythons map()
function to cast each list element to another type.
(Recommended micro-course: python3 basic micro-course)
squares = { x**2 for x in range(6) if x < 4 }
# print(squares) >> {0, 1, 4, 9}
The same is true for collections.
In addition to inline
for
loops, you can even add conditions directly!
# phrase = 'deleveled'
isPalindrome = phrase == phrase[::-1]
# print(isPalindrome) >> true
A reply is a series of characters that read the same characters forward and backward. I
f a given string is an echo, some loops and conditions are usually required to check. I
n
Python
you only need to compare the string with its reverse string.
In addition to using the slice operator
[::-1]
you can also use
reverse()
function to reverse the string.
That's some of the knowledge about
Python
one-line code, and I hope it's helpful.
Original English: dev.to/devmount/10-awesome-pythonic-one-liners-explained-3doc