python list index out of range?

Question

My task is to read a .csv file and take the average of the 4th columns of the data and also take the sum of the 8th data in January, which is line 13-31 from the csv file. This is my current code; it keeps telling me index out of range for line 11 and 12,how come? and as well, is there anything else wrong in my code?

file = open("citi_bike.csv", 'r')
data = []
for line in file:
  parts = line.strip().split()
  data.append(parts)

def print_detail(data):
    avg = 0
    total = 0
    for record in data:
      avg += float(record[3])
      total += float(record[7])
    avg /= len(data)
    print("\nThe following data is from " + data[0][0] + " to " + data[-1][0])
    print'\naverage miles:',(avg)
    print'\ntotal number of pass purchased:',(total)

print_detail([r for r in data if r[0].split('/')[0]=='1'])

Answer 1

If I understand what you've tried to do, record is an element of data, thus, record[3] and record[7] do not exist. You want to sum up the elements of the fourth and 8th columns of data not record.

I have another advice: you can use the read_csv method of the pandas library which is very powerful and fast. In one line you download the data and then use the sum function of numpy library.