DataFrame.astype()

dtype : data type, or dict of column name -> data type

Use a numpy.dtype or Python type to cast entire pandas object to the same type. Alternatively, use {col: dtype, ...}, where col is a column label and dtype is a numpy.dtype or Python type to cast one or more of the DataFrame?s columns to column-specific types.

raise_on_error : raise on invalid input

kwargs : keyword arguments to pass on to the constructor