如何使用python对CSV文件进行排序

Question

I am trying to make a leader board for my python program I have sorted out writing the different scores to the leader board already However, I am having trouble finding a way that I can sort this data (Highest score at the top and lowest at the bottom)

Also, I am sorry but I do not have any code that is even vaguely functional, everything I have tried has just been incorrect

Also I only have limited access to modules as it is for a school project which makes it even harder for me (I have CSV,Random,Time,)

Thank you so much I would really appreciate any help I can recieve

Answer 1

You can read in the file with pandas, sort it by a column, and overwrite the old csv with the new values. The code would look similar to this:

import pandas as pd

path = your_file_path

df = pd.read_csv(path)

df = df.sort_values(by=["column_name"], ascending=False)

df.to_csv(path)

Answer 2

This problem can be done in 3 parts using standard Python:

1. Read all of the data (assuming it has a header row). A csv_reader() is used to parse your file and read in each row as a list of values. By calling list() it will read all rows as a list of rows.
2. Sort the data
3. Write all of the data (add back the header first), this time using a csv.writer() to automatically take your list of rows and write the correct format to the file.

This can be done using Python's csv library which you say you can use. Secondly you need to tell the sort() function how to sort your rows. In this example it assumes the scores are in the second column. The csv library will read each row as a list of values (starting from 0), so the score in this example is column 1. The key parameter gives sort() a function to call for each row that it is sorting. The function receives a row and returns which parts of the row to sort on, that way you don't have to sort on the first column. lambda is just shorthand for writing a single line function, it takes a parameter x and returns the elements from the row to sort on. Here we use a Python tuple to return two elements, the score and the name. First convert the score string x[1] into an integer. Adding a - will make the highest score sort to the top. x[0] then uses the Name column to sort for cases where two scores are the same:

import csv

with open('scores.csv', newline='') as f_input:
    csv_input = csv.reader(f_input)
    header = next(csv_input)
    data = list(csv_input)

data.sort(key=lambda x: (-int(x[1]), x[0]))

with open('scores_sorted.csv', 'w', newline='') as f_output:
    csv_output = csv.writer(f_output)
    csv_output.writerow(header)
    csv_output.writerows(data)

So for a sample CSV file containing:

name,score
fred,5
wilma,10
barney,8
betty,4
dino,10    

You would get a sorted output CSV looking like:

name,score
dino,10
wilma,10
barney,8
fred,5
betty,4

Note, dino and wilma both have the same score, but dino is alphabetically first.

This assumes you are using Python 3.x