python - Performing calculations on a tab-delimited file -

i'm still learning python , still don't know how work arrays.

i'm want read tab-delimited file example (but in case have 400 rows):

  col1      col2   0.0001    0.6   0.0001    0.5   0.000006  0.8   0.0001    0.0003   0.002     1   0.002     3 

i want following output:

col1      col2 0.0001    0.36676667 0.000006  0.8 0.002     2 

so wanna keep same value in col1 taking mean of values in col2 corresponds same value in col1.

i can read array using :

  arr = np.genfromtxt('test.csv', dtype=none, delimiter='\t', skiprows=1) 

but don't know how make these operations , making new file new generated data.

thanks lot help!

use collections.defaultdict list default argument.

take value first column key, , append second value.

import csv collections import defaultdict  # gather data csv file d = defaultdict(list) open('data.csv', 'r') csvfile:     reader = csv.reader(csvfile, delimiter='\t')     row in reader:         d[float(row[0])].append(float(row[1]))  # print mean. k in d.keys():     print k, sum(d[k])/len(d[k])