Question

i have a .csv data set (like 15000 items) and i want to find the minimum value.

As i’ve been searching for an answer, I’ve found a lot of answers, but people always have the data set they want to find the minimum value of in brackets

ex. [0.0, 1.3, 37.7]

and then ask Python to find the minimum value. With such a large data set, i cant possibly individually place the data into brackets, how can i call out a specific column in my .csv file and then find the minimum value?

(please explain what you are doing, too, i am very new to working with python)

Answer 1

• 15,000 items is not ‘large’; I have dealt with some 12 million line .csv files in memory (although I had to use 64-bit Python to get enough space!)

• min() will work against a generator – that is, one item at a time, instead of all at once

.

import csv

with open('myfile.csv', 'rb') as inf:
    incsv = csv.reader(inf)
    column = 1                # the second column (Python counts from 0, per @MRAB's comment)
    datatype = float          # or int, as appropriate (per MvG)
    data = (datatype(row[column]) for row in incsv)    # NB: a generator expression, not a list
    least_value = min(data)