如何计算字符串中字符出现的次数?
如。“a”在“Mary had a little lamb”中出现了4次。
如何计算字符串中字符出现的次数?
如。“a”在“Mary had a little lamb”中出现了4次。
当前回答
要获得所有字母的计数,请使用集合。计数器:
>>> from collections import Counter
>>> counter = Counter("Mary had a little lamb")
>>> counter['a']
4
其他回答
myString.count('a');
更多信息请点击这里
我不知道“最简单的”,但简单的理解可以做到:
>>> my_string = "Mary had a little lamb"
>>> sum(char == 'a' for char in my_string)
4
利用内置的和,生成器理解和bool是整数的子类的事实:如何乘字符等于'a'。
正则表达式?
import re
my_string = "Mary had a little lamb"
len(re.findall("a", my_string))
我是pandas库的粉丝,尤其是value_counts()方法。你可以用它来计算字符串中每个字符的出现次数:
>>> import pandas as pd
>>> phrase = "I love the pandas library and its `value_counts()` method"
>>> pd.Series(list(phrase)).value_counts()
8
a 5
e 4
t 4
o 3
n 3
s 3
d 3
l 3
u 2
i 2
r 2
v 2
` 2
h 2
p 1
b 1
I 1
m 1
( 1
y 1
_ 1
) 1
c 1
dtype: int64
最简单的方法是一行代码:
'Mary had a little lamb'.count("a")
但是如果你想用这个也可以:
sentence ='Mary had a little lamb'
count=0;
for letter in sentence :
if letter=="a":
count+=1
print (count)