Converting vertical headers to horizontal in csv

Question

I am new to Python. I have a csv file which will generate the file in below format:

Timestamp for usage of CPU
1466707823  1466707828  1466707833

Percent use for CPU# 0
0.590551162 0.588235305 0.59055119

Percent use for CPU# 1
7.874015497 7.843137402 7.67716547

But I need to generate csv file in this format:

Timestamp for usage of CPU    Percent use for CPU# 0    Percent use for CPU# 1

1466707823                    0.590551162               7.874015497

1466707823                    0.588235305               7.843137402

1466707828                    0.59055119                7.67717547

I am not getting any idea how to proceed further. Could any one please help me out with this?

Answer 1

It seems like the simplest way to do it would be to first read and convert the data in the input file into a list of lists with each sublist corresponding to a column of data in the output csv file. The sublists will start off with the column's header and then be followed by the values associated with it from the next line.

Once that is done, the built-in zip() function can be used to transpose the data matrix created. This operation effectively turns the columns of data it contains into the rows of data needed for writing out to the csv file:

import csv

def is_numeric_string(s):
    """ Determine if argument is a string representing a numeric value. """
    for kind in (int, float, complex):
        try:
            kind(s)
        except (TypeError, ValueError):
            pass
        else:
            return True
    else:
        return False

columns = []
with open('not_a_csv.txt') as f:
    for line in (line.strip() for line in f):
        fields = line.split()
        if fields:  # non-blank line?
            if is_numeric_string(fields[0]):
                columns[-1] += fields  # add fields to the new column
            else:  # start a new column with this line as its header
                columns.append([line])

rows = zip(*columns)  # transpose
with open('formatted.csv', 'w') as f:
    csv.writer(f, delimiter='\t').writerows(rows)