Note: the following tips are based on Python 3

Exchange variable value

a, b = 1, 2
print("Assignment:", a, b)

# Exchange variable value
a, b = b, a
print("Exchange:", a, b)

Assignment: 1 2
 Exchange: 2 1

Chain comparison

a = 5
print(1 < a < 10)
print(5 < a < 10)

True
False

String format f-Strings

# Python 3.6 starts to support
name = "Jack"
print(f"Hello {name}")

Hello Jack

Number of string splits

# For example, divide the url with "/", only once from the right side, to get the final path
url = "http://www.test.com/page/page/12345"

# Split once with "/" from the right
result = url.rsplit('/', 1)
print(result)

# Take the second element
print(result[1])

['http://www.test.com/page/page', '12345']
12345

Get the last element in the list

a = [1, 2, 3]

# Last element
print(a[-1])

3

Remove duplicates from list

a = [1, 2, 4, 5, 5, 7, 4, 9]
# duplicate removal
a = list(set(a))
print(a)

[1, 2, 4, 5, 7, 9]

Reverse list

a = [1, 2, 3]

# reversal
b = a[::-1]
print(b)

[3, 2, 1]

Number of statistical elements

from collections import Counter

a = ['a','a','b','b','b','c','d','d','d','d','d']
count = Counter(a) 
print(count) 

Counter({'d': 5, 'b': 3, 'a': 2, 'c': 1})

Concatenate the list into a string with commas (or any other character)

a = ['a', 'b', 'c']
print(','.join(a))

a,b,c

Get element index on loop list

a = ['a', 'b', 'c']
for index,v in enumerate(a):
    print(index, v)

0 a
1 b
2 c

Get the same item in two lists

l1 = [1, 2, 3, 4, 5]
l2 = [1, 2, 5, 6, 7, 8]
l = list(set(l1) & set(l2))
print(l)

[1, 2, 5]

Get the first, last, and middle parts of the list

a = [1, 2, 3, 4, 5]
first, *rest, last = a
print(first)
print(rest)
print(last)

1
[2, 3, 4]
5

Converting a secondary list to a primary list

a = [[1, 2], [3, 4]]

# Convert to first level list
b = [x for _list in a for x in _list]
print(b)

[1, 2, 3, 4]

Combine two linked lists into one list

l1 = [1, 2]
l2 = [3, 4]

# Method 1: merge the list into another list
l3 = l1 + l2
print(l3)

# Method 2: merge list 2 into List 1
l1.extend(l2)
print(l1)

[1, 2, 3, 4]
[1, 2, 3, 4]

Combine two lists into a dictionary

l1 = ['a', 'b', 'c']
l2 = [1, 2, 3]
d = dict(zip(l1, l2))
print(d)

{'a': 1, 'b': 2, 'c': 3}

Dictionary sort by value

d = {"a": 3, "b": 4, "c": 2, "d": 1}

reversed_d = sorted(d.items(), key=lambda item: item[1])
print(reversed_d)

[('d', 1), ('c', 2), ('a', 3), ('b', 4)]

Set default values in dictionary

d = {'a': 1, 'b': 2}

# If not, set default
d.setdefault('c', 3)
print(d)

# If it already exists, it will not be updated
d.setdefault('b', 3)
print(d)

{'a': 1, 'b': 2, 'c': 3}
{'a': 1, 'b': 2, 'c': 3}

Dictionary get method

d = {'a': 1, 'c': 3}

print(d.get('c', 33))

# get method. If the key does not exist, take the following default value
print(d.get('b', 33))

3
33

Key inversion in dictionary

d = {1: 'a', 2: 'b', 3: 'c'}
invert_d = {v: k for k, v in d.items()}
print(invert_d)

{'a': 1, 'b': 2, 'c': 3}

Get common items in two dictionaries

d1 = {'a': 1, 'b': 2, 'c': 3}
d2 = {'b': 4, 'c': 3, 'd': 6}

# Common key
print(d1.keys() & d2.keys())

# Common key value pair
print(d1.items() & d2.items())

{'c', 'b'}
{('c', 3)}

Merge two dictionaries into one

d1 = {'a': 1}
d2 = {'b': 2}

# Merge dictionary
d3 = {**d1, **d2}

print(d3)

{'a': 1, 'b': 2}

For else statement

for i in [1, 2, 3]:
    if i == 0:
        break
else:
    print("Not implemented break")

break not performed

While-Else

i = 5
while i > 1:
    print(i)
    i -= 1
else:
    # Note: when there is a break in while, the following will not be executed in else. This is different from for else, which is worth noting
    print("End of cycle")

5
4
3
2
 End of cycle

Try except else statement

In Python, you can simply use try exception statement to handle error exceptions. In fact, you can add an else statement, which refers to the statement that runs after the try statement is executed when no exception occurs. In addition, if you need to run code that needs to be executed to find exceptions, you can use finally, for example:

a, b = 1,2

try:
    print(a/b)
except Exception as _:
    print(e)
else:
    print("No exception occurred")
finally:
    print("Execute whether or not an exception occurs")

0.5
 No exception occurred
 Execute whether or not an exception occurs

Get current folder name

import os

os.path.basename(os.getcwd())

'fun_of_python'

The above are some tips for sorting out. I hope they can help you. Welcome to make additional communication~