python - 如何计算 Python 数组中指定单词的出现次数？

Question

我正在开发一个用户输入文本的小程序，我想检查给定输入中给定单词出现了多少次。

# Read user input
print("Input your code: \n")

user_input = sys.stdin.read()
print(user_input)

比如我在程序中输入的文字是:

a=1
b=3
if (a == 1):
    print("A is a number 1")
elif(b == 3):
    print ("B is 3")
else: 
    print("A isn't 1 and B isn't 3")

要查找的单词在数组中指定。

wordsToFind = ["if", "elif", "else", "for", "while"]

基本上我想打印输入中出现了多少个“if”、“elif”和“else”。

如何统计用户输入的给定字符串中“if”、“elif”、“else”、“for”、“while”等词的出现次数？

Answer 1

我认为最好的选择是使用 python 的内置模块 tokenize:

# Let's say this is tokens.py
import sys
from collections import Counter
from io import BytesIO
from tokenize import tokenize

# Get input from stdin
code_text = sys.stdin.read()

# Tokenize the input as python code
tokens = tokenize(BytesIO(code_text.encode("utf-8")).readline)

# Filter the ones in wordsToFind
wordsToFind = ["if", "elif", "else", "for", "while"]
words = [token.string for token in tokens if token.string in wordsToFind]

# Count the occurrences
counter = Counter(words)

print(counter)

测试

假设您有一个 test.py:

a=1
b=3
if (a == 1):
    print("A is a number 1")
elif(b == 3):
    print ("B is 3")
else: 
    print("A isn't 1 and B isn't 3")

然后你运行:

cat test.py | python tokens.py

输出:

Counter({'if': 1, 'elif': 1, 'else': 1})

优势

• 只有正确的 python(语法上)才会被解析

• 您只会计算 python 关键字(不是每次 if 出现在代码文本中，例如，您可以有这样一行

  a = "if inside str"

  我认为if不应该被计算在内