Answers for "pandas all int columns to int32"

column dataframe to int

df[[column_name]].astype(int)

get int64 column pandas

# Use select_dtypes with np.number for select all numeric columns:
cols = [df.select_dtypes([np.number]).columns]
print (list(cols))

# Here is possible specify float64 and int64:
cols = [df.select_dtypes([np.int64,np.float64]).columns]
print (cols)