김예린 김예린 - 1 month ago 17
Python Question

Python : could not convert string to float error

I have csv file with [NEAR_DIST] (<-row 7). I would like to know how can I get the mean and STD of this array.

I used csv and numpy:

# -*- coding: utf-8 -*-
import csv
import numpy

with open('C:\\test.csv') as csvfile:
readCSV = csv.reader(csvfile, delimiter=',')
distance = []
distance.append(float(x) for x in csvfile)
for row in readCSV:
distance = row[7]
a = numpy.array(distance, dtype = 'float_')
b = numpy.sum(a)
print(b)

AJK AJK
Answer

The question is a little unclear. My assumption is that you have some data of the form:

01,02,03,04,05,06,07,08,09,..
11,12,13,14,15,16,17,18,19,..
21,22,23,24,25,26,27,28,29,..
and you want to find the sum of elements in the 7th column. i.e. 7 + 17 + 27 + ... in this example.

This should work:

import numpy
data = numpy.genfromtxt("a.csv", delimiter=",")
data[:, 6].sum() # 6 because indices start from 0 in python