How can I match everything except for the expression with a regex?

I have the following text:

MSH 1A C3
MSH B4-14 c3-1
AU1 C4 2
MA2A C1 1

And I want to take this information from it:

MSH 1A
MSH B4-14
AU1
MA2A

I tried this regex to highlight the C’s:

(( C[0-9].*)|( c[0-9].*))

How can I match everything except for what I highlighted in my regex? This needs to be a one-line regex.

>Solution :

You can shorten the pattern using a charaxcter class [Cc].

Using replace with an empty string:

df_elements['POINT_ID'] = df_elements['POINT_ID'].str.replace(r'\s[Cc]\d.*', "")

Using extract with a capture group:

df_elements['POINT_ID'] = df_elements['POINT_ID'].str.extract('^(.*?)(?=\s*[Cc]\d)', expand=False)

Both will result in:

    POINT_ID
0     MSH 1A
1  MSH B4-14
2        AU1
3       MA2A