Finding Max value in a column of csv file PYTHON

Question

I'm fairly new to coding, and I'm stuck on a current project. I have a .csv file, and rather than use a spreadsheet, I'm trying to write a python program to find the maximum value of a specific column. So far I have the following:

import csv

with open('american_colleges__universities_1993.csv', 'rU') as f:
    reader = csv.reader(f)
    answer = 0
    for column in reader :
        answer = 0
        for i in column[14]:
            if i>answer:
                answer = i
print answer

I keep getting something like:

The problem is that this is only returning the largest integer (which happens to be 9), when it should be returning something like 15,000. I suspect the program is only looking at each digit as its own value... How can I get it to look at the entire number in each entry?

Sorry for the newb question. Thanks!

AChampion · Accepted Answer · 2016-02-11 05:14:14Z

5

Currently you are comparing each character in column[14] and setting the lexically maximum character to answer. Assuming you want to arithmetically compare the whole of column[14] you will need to replace the comma with '' and convert to int, e.g.:

with open('american_colleges__universities_1993.csv', 'rU') as f:
    reader = csv.reader(f)
    next(reader)     # Skip header row
    answer = max(int(column[14].replace(',', '')) for column in reader)
print answer

If you need the whole row that has the maximum column[14] you could alternatively use the key argument to max:

    answer = max(reader, key=lambda column: int(column[14].replace(',','')))
print answer

edited Feb 11, 2016 at 5:14

answered Feb 11, 2016 at 2:11

AChampion

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2 Comments

Jhiems Over a year ago

So, the first row in the column is text. How can I skip it to look at the actual number? I've tried next(f)

AChampion Over a year ago

You can next(reader) before the max call to skip the header line. Alternatively you can look into DictReader and then use column['ColumnName'].

Python NWB · Accepted Answer · 2019-04-13 17:13:25Z

2

import csv
with open('american_colleges__universities_1993.csv', 'r') as f:
    reader = csv.reader(f)
    maxnum = max(reader, key=lambda row: int(row[14]))
print(maxnum)

This should do the work for you.

answered Apr 13, 2019 at 17:13

Python NWB

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