ENH: Improve error message for read_csv header argument containing non int types. GH16338.

Adds error "header must be integer or list of integers" when the header argument is a list, tuple or numpy array containing non-integers. Initially intended to read_csv, but applies to other functions with similar header arguments. GH16338 refers to a case in which the user mixes up the "names" and "header" arguments.

Author: mjlove12

pandas/io/parsers.py

@@ -1164,6 +1164,8 @@ def __init__(self, kwds):
         # validate header options for mi
         self.header = kwds.get('header')
         if isinstance(self.header, (list, tuple, np.ndarray)):
+            if not all(map(is_integer, self.header)):
+                raise ValueError("header must be integer or list of integers")
             if kwds.get('as_recarray'):
                 raise ValueError("cannot specify as_recarray when "
                                  "specifying a multi-index header")
@@ -1183,7 +1185,7 @@ def __init__(self, kwds):
                         is_integer(self.index_col)):
                     raise ValueError("index_col must only contain row numbers "
                                      "when specifying a multi-index header")
-
+                    
         self._name_processed = False
 
         self._first_chunk = True