排序和排序列Python

Question

我有一个代码，可以使用另一个CSV文件中的信息来创建CSV。 在我的新CSV文件中，我只想保存20行，从行的最高到最低排序row ['impressions']

我读了一些关于熊猫的东西，但是却找不到任何关于熊猫的知识！

更清楚地说，我分享了一些图片：

之前： 在此处输入图片描述

之后： 在此处输入图片描述

码：

import csv
input_file = 'report_2017_12_11_12_31_19UTC.csv'
output_file= "All_Data_Tags.csv"

with open(input_file) as csvfile, open(output_file,  "w") as output:
    reader = csv.DictReader(csvfile)
    cols = ("domain","ddomain","opportunities", "impressions", "fillRate", "DATA")
    writer = csv.DictWriter(output, fieldnames=cols, extrasaction='ignore')

    writer.writeheader()
    for row in reader:
        row['fillRate'] = '{:.2f}'.format(float(row['fillRate']) * 100)
        if row['ddomain']  == "":
            if row['domain']  == "":
                row['ddomain'] = "App"
                row['domain'] = " "
        if row['domain'] == row['ddomain']:
            row['domain'] = "Real Site"    
        if row['domain']  == "":
            row['domain'] = "Detected Only"
        if row['ddomain']  == "":
            row['ddomain'] = "Vast Media"
        if row['ddomain'] != row['domain']:
            if row['ddomain'] != "Vast Media":
                if row['domain'] != "Real Site":
                    if row['domain'] != "Detected Only":
                        if row['ddomain'] != "App":
                            row['DATA'] = "FAKE"
                        else:
                            row['DATA'] = "OK"
                    else:
                        row['DATA'] = "OK"
                else:
                    row['DATA'] = "OK"
            else:
                row['DATA'] = "OK"

        writer.writerow(row)

Answer 1

这是答案：

码：

import pandas as pd 


movies = pd.read_csv('Top20_Media_Yesterday.csv')

movies = movies.sort_values(['impressions'], ascending=False)

movies = movies.to_csv("Top20_Media_Yesterday.csv")

movies = pd.read_csv('Top20_Media_Yesterday.csv', nrows=21)

movies = movies.to_csv("Top20_Media_Yesterday.csv")

Answer 2

使用pandas框架的DataFrame.sort_values函数，将要排序的列名传递给by参数，并将axis设置为1。

您可以在此处找到类似的示例。