one,two,three
1,2,3
2,3,4
3,4,5

,two,three
,2,3
,3,4
,4,5

import csv

with open('code.csv', 'rb') as input, open('result.csv', 'wb') as output:
        reader = csv.DictReader(input)
        rows = [row for row in reader]
        writer = csv.writer(output, delimiter = ',')

        writer.writerow(["new_one", "new_two", "new_three"])

        for row in rows:
                if 'two' in row:
                        writer.writerow(['',row["two"]])

        for row in rows:
                if 'one' in row:
                        writer.writerow([row["one"]])

new_one,new_two,new_three
,2
,3
,4
1
2
3

for row in rows:
                    if 'one' in row:
                            writer.writerow([row["one"]])

new_one,new_two,new_three
1,2
2,3
3,4

for row in rows:
                if 'one' in row and 'two' in row:
                        writer.writerow([row["one"],row["two"]])

for row in rows:
        writer.writerow([row.get("one", ""), row.get("two", "")])