"If 语句：字符串在 Python\/pandas 中以 4 个数字开头"

Question

I have a column of a dataframe consisting of strings, which are either a date (eg "12-10-2020") or a string starting with 4 digits (eg "4030 - random name"). I would like to write an if statement to capture the strings which are starting with 4 digits, which is similar to this code:

string[0].isdigit()

Answer 1

使用str.contains<\/code> : col"

df[df["col"].str.contains(r'^[0-9]{4}')]

Answer 2

You can use str.match<\/code><\/a> that is anchored by default to the start of the string:

df = pd.DataFrame({'col': ['4030 - random name', 'other', '07-02-2022']})

df[df['col'].str.match('\d{4}')]