Pandas Dataframe filter rows by only one column

Question

I want to filter a dataframe by only keeping the rows that conform with a regex pattern in a given column. The example in the documentation only filters by looking for that regex in every column in the dataframe ( documentation to filter )

So how can i change the following example

df.filter(regex='^[\d]*', axis=0)

to something like this: (Which only looks for the regex in the specified column)

df.filter(column='column_name', regex='^[\d]*', axis=0)

Answer 1

使用从给定列和正则表达式模式制作的布尔掩码过滤DataFrame，如下所示： df[df.column_name.str.contains('^[\\d]*', regex=True)]

Answer 2

Use the vectorized string method contains() or match() - see Testing for Strings that Match or Contain a Pattern :

df[df.column_name.str.contains('^\d+')]

or

df[df.column_name.str.match('\d+')]    # Matches only start of the string

Note that I removed superfluous brackets ( [] ), and replaced * with + , because the \\d* will always match as it matches a zero occurrences, too (so called a zero-length match .)