Sort a CSV file to read in Python Program

Question

I'm trying to create a leaderboard in python, where a player will get a score from playing a game, which will write to a .csv file. I then need to read from this leaderboard, sorted from largest at the top to smallest at the bottom. Is the sorting something that should be done when the values are written to the file, when i read the file, or somewhere in between?

my code:

writefile=open("leaderboard.csv","a")
writefile.write(name+", "points)
writefile.close()

readfile=open("leaderboard.csv","r")

I'm hoping to display the top 5 scores and the accompanying names. It is this point that I have hit a brick wall. Thanks for any help.

Edit: getting the error 'list index out of range'

import csv

name = 'Test'
score = 3

with open('scores.csv', 'a') as f:
    writer = csv.writer(f)
    writer.writerow([name, score])

with open('scores.csv') as f:
    reader = csv.reader(f)
    scores = sorted(reader, key=lambda row: (float(row[1]), row[0]))
    top5 = scores[-5:]

csv file:

test1   3

test2   3

test3   3

Answer 1

Python has a csv module in the standard library. It's very simple to use:

import csv

with open('scores.csv', 'a') as f:
    writer = csv.writer(f)
    writer.writerow([name, score])

with open('scores.csv') as f:
    reader = csv.reader(f)
    scores = sorted(reader, key=lambda row: (float(row[1]), row[0]))
    top5 = scores[-5:]

Is the sorting something that should be done when the values are written to the file, when i read the file, or somewhere in between?

Both approaches have their benefits. If you sort when you read, you can simply append to the file, which makes writing new scores faster. You do take more time when reading as you have to sort it before you can figure out the highest score, but in a local leaderboard file this is unlikely to be a problem as you are unlikely to have more than a few thousands of lines, so you'll likely be fine with sorting when reading.

If you sort while writing, this comes with the problem that you'll have to rewrite the entire file every time a new score is added. However, it's also easier to cleanup the leaderboard file if you sort while writing. You can simply remove old/low scores that you don't care about anymore while writing.

Answer 2

Try this:

import pandas as pd
df = pd.read_csv('myfullfilepath.csv', sep=',', names=['name', 'score'])
df = df.sort_values(['score'], ascending=False)
first_ten = df.head(10)
first_ten.to_csv('myfullpath.csv', index=False). 

I named the columns like that , following the structure tat you suggested.