20 Essential Python Tips to Boost Your Programming Efficiency

1. String Reversal Use slicing to reverse a string.

str1 = "qwert"
rev_str1 = str1[::-1]  # output: trewq

2. Capitalize First Letter Convert a string to title case with the title() method.

str1 = "this is a book"
print(str1.title())  # Output: This Is A Book

3. Find Unique Elements in a String Create a set from the string and join its elements.

str1 = "aabbccccdddd"
set1 = set(str1)
new_str = ''.join(set1)
print(new_str)

4. Repeat a String or List Use the * operator to duplicate a string or list multiple times.

i = 4
str1 = "abcd"
list1 = [1, 2]
print(str1 * i)   # abcdabcdabcdabcd
print(list1 * i)  # [1, 2, 1, 2, 1, 2, 1, 2]

5. List Comprehension Build a new list by applying an expression to each element of an existing list.

list1 = [1, 2, 3]
new_list1 = [2 * i for i in list1]
print(new_list1)  # [2, 4, 6]

6. Swap Variables Without a Temporary Variable Use tuple unpacking.

x = 1
y = 2
x, y = y, x
print(x)  # 2
print(y)  # 1

7. Split a String into a List of Sub‑strings Use the split() method with an optional delimiter.

str1 = "This is a book"
str2 = "test/ str 2"
print(str1.split())          # ['This', 'is', 'a', 'book']
print(str2.split('/'))      # ['test', ' str 2']

8. Join a List of Strings into a Single String Use join() with a separator.

list_str = ['This', 'is', 'a', 'book']
print(','.join(list_str))  # This,is,a,book

9. Check for Palindrome Strings Compare a string with its reversed version.

str1 = "qqaabb"
if str1 == str1[::-1]:
    print("回文")
else:
    print("不是")

10. Count Elements in a List Use collections.Counter to obtain frequencies and the most common element.

from collections import Counter
list1 = ['a', 'b', 'a', 'c', 'c', 'c']
count = Counter(list1)
print(count)                # Counter({'c': 3, 'a': 2, 'b': 1})
print(count['b'])          # 1
print(count.most_common(1))# [('c', 3)]

11. Determine Whether Two Strings Are Anagrams Compare their Counter objects.

s1, s2, s3 = "acbde", "abced", "abcda"
c1, c2, c3 = Counter(s1), Counter(s2), Counter(s3)
if c1 == c2:
    print('1和2是异序词')
if c1 == c3:
    print('1和3是异序词')

12. Use a try‑except‑else Block Execute code that may raise an exception and run the else clause when no exception occurs.

a, b = 1, 0
try:
    print(a / b)
except ZeroDivisionError:
    print("除数为0")
else:
    print("不存在异常")
finally:
    print("此段总是会执行")

13. Enumerate to Get Index‑Value Pairs Iterate over a list with both index and value.

list1 = ['a', 'b', 'c', 'd', 'e']
for idx, val in enumerate(list1):
    print('{0}:{1}'.format(idx, val))
# 0:a
# 1:b
# 2:c
# 3:d
# 4:e

14. Get Memory Usage of an Object Use sys.getsizeof().

import sys
num = 21
print(sys.getsizeof(num))

15. Merge Two Dictionaries In Python 3, use the unpacking operator **.

dic1 = {'app': 9, 'banana': 6}
dic2 = {'banana': 4, 'orange': 8}
com_dict = {**dic1, **dic2}
print(com_dict)  # {'app': 9, 'banana': 4, 'orange': 8}

16. Measure Code Execution Time Use time.time() and calculate the difference in microseconds.

import time
s_time = time.time()
a, b = 1, 2
c = a + b
e_time = time.time()
time_taken_in_micro = (e_time - s_time) * (10**6)
print("程序运行的毫秒：{0} ms".format(time_taken_in_micro))

17. Flatten Nested Lists Use iteration_utilities.deepflatten for unknown depth or a simple list comprehension for one‑level nesting.

from iteration_utilities import deepflatten
l = [[1,2,3],[4,[5]],[6,7]]
print(list(deepflatten(l, depth=3)))
# [1,2,3,4,5,6,7]

18. Random Sampling from a List Use random.sample() or secrets.SystemRandom() for cryptographically secure samples.

import random
list1 = ['a','b','c','d','e']
ns = 2
samples = random.sample(list1, ns)
print(samples)  # e.g., ['a', 'c']

import secrets
s_rand = secrets.SystemRandom()
samples = s_rand.sample(list1, ns)
print(samples)  # e.g., ['c', 'd']

19. Convert an Integer to a List of Digits Use map(int, str(num)) or a list comprehension.

nums = 123456
digit_list = list(map(int, str(nums)))
print(digit_list)  # [1,2,3,4,5,6]

digit_list = [int(x) for x in str(nums)]
print(digit_list)  # [1,2,3,4,5,6]

20. Check Uniqueness of Elements in a List Compare the length of the list with the length of its set.

def unique(l):
    if len(l) == len(set(l)):
        print("所有元素是唯一的")
    else:
        print("存在重复")

unique([1,2,3,4])  # 所有元素是唯一的
unique([1,1,3,4])  # 存在重复