python regex with multiple recursive characters

Question

I have the following pandas series:

arr = pd.Series(['C', 'A', 'T', 'G', 'CC', 'KEEP', 'ATC', 'CACACAC', 'CCCCCCCCACAGTTTATGTAG', 'C(2', 'Cor CC', 'AC or ACC'])

From it, I want to remove the elements C(2, Cor CC and AC or ACC using regex

So the criteria that I am trying to match are:

1. Start with a capital letter: ^[A-Z]
2. Exclude any element that has a parenthesis in it: [^\(]
3. Exclude any element that has the string or

arr.str.contains(r'^[A-Z][\(]') will match C(2 whereas I can match Cor CC and AC or ACC with arr.str.contains(r'\w*or.\w*'.

I can then pop out these elements from my list, but I am trying to keep the elements of interest (i.e. without C(2, Cor CC and AC or ACC) using regular expression

Answer 1

You may use

arr[~arr.str.contains(r'^[A-Z]\(|or')]

Details

• ^[A-Z]\( - an uppercase ASCII letter and ( at the start of a string
• | - or
• or - an or substring

See the regex demo.