Python script 1

Python script:
import numpy as np

data = np.genfromtxt('inputcsv', delimiter=',')
keys = sorted(set(data[:,0]))

result = np.array([])

for k in keys:
    col = data[np.where(data[:,0] == k)][:,1]
    if not result.any():
        result = col
    else:
        result = np.vstack((result, col))
    print('key {0} finished'.format(k))

np.savetxt('final.csv', np.transpose(result), delimiter=',')

Input file:
Column A | Column B
      10 |      0.1
      10 |      0.2
      10 |      0.3
      20 |      0.4
      20 |      0.5
      20 |      0.6

Command:
python script.py

Output:
Traceback (most recent call last):
  File "script.py", line 4, in <module>
    keys = sorted(set(data[:,0]))
IndexError: too many indices for array