convert variable to column in pandas code example

Example 1: convert column to numeric pandas

# convert all columns of DataFrame
df = df.apply(pd.to_numeric) # convert all columns of DataFrame

# convert just columns "a" and "b"
df[["a", "b"]] = df[["a", "b"]].apply(pd.to_numeric)

Example 2: change dataframe column type

>>> df.astype({'col1': 'int32'}).dtypes
col1    int32
col2    int64
dtype: object