reader = csv.reader(open('somefile.csv'))
header = next(reader)
res_list = [[] for _ in header]
for row in reader:
    for i, val in enumerate(row):
        res_list[i].append(float(val))
result_dict = dict((n, res_list[i]) for i, n in enumerate(header))
Pythonic способ заполнить массив numpy