在 Python 中的字符串中获取另一个字符之前的字符

Question

The thing I am trying to achieve is that I want to get the character before another one in a string. For eg, if the string is "a0c1e2g3", I want to get what's written in the index[0] by just having the index[1] like i want to get the value of the index[0] ("a") when I only have the value of index[1] ("1"). I want it for all characters. I want the string to be extendable too.

Expected result:

a
c
e
g

The result I could get till:

0
2
4
6

The code I tried:

s = "a0c1e2g3"
for c, i in enumerate(s):
    if i.isdigit():
        alpha_before_int = c-1
        print(alpha_before_int)
        # I want to get "a", "c", "e", "g"

Answer 1

>>> s = "a0c1e2g3"
>>> for c, i in enumerate(s):
...     if i.isdigit():
...         alpha_before_int = s[c-1]
...         print(alpha_before_int)
...         # I want to get "a", "c", "e", "g"
... 
a
c
e
g
>>> 

Answer 2

You can use zip :

[c for c, n in zip(s, s[1:]) if n.isdigit()]

Or using re :

re.findall('(.)\d', s)

---

['a', 'c', 'e', 'g']