在python中排序不起作用[重复]

Question

这是我的完整代码示例：

import csv
import operator

f=open('C://Users//ganesha//Desktop//b//sampleDataCsv.csv',"r")
readerObject1 = csv.reader(f,delimiter = ",")    
inputList = list(readerObject1)    
print("Input",inputList)

sortedList = sorted(inputList,key=operator.itemgetter(0),reverse=True)

print("Output",sortedList)

f1=open('C://Users//ganesha//Desktop//b//sampleDataCsv4.csv',"w+") 
writerObject=csv.writer(f1,delimiter=",",lineterminator='\n')

writerObject.writerows(sortedList)

我的输入如下所示：

[['20'], ['12'], ['13'], ['11'], ['14'], ['15'], ['19'], ['1'], ['2'], ['4'], ['9'], ['0'], ['8'], ['7'], ['5'], ['6'], ['3'], ['16'], ['17'], ['10']]

我的输出是这样的：

[['9'], ['8'], ['7'], ['6'], ['5'], ['4'], ['3'], ['20'], ['2'], ['19'], ['17'], ['16'], ['15'], ['14'], ['13'], ['12'], ['11'], ['10'], ['1'], ['0']]

Answer 1

嗯，那是因为您正在对代表数字的strs 进行排序。创建一个小的 lambda 获取项目并将其强制转换为 int 以获得基于 int 值的排序：

k = lambda x: int(x[0])    
sortedList = sorted(inputList,key=k,reverse=True)

现在sortedList 根据int 值排序：

[['20'], ['19'], ['17'], ['16'], ['15'], ['14'], ['13'], ['12'],
 ['11'], ['10'], ['9'], ['8'], ['7'], ['6'], ['5'], ['4'], ['3'],
 ['2'], ['1'], ['0']]

如果您不介意一些卷积，请将 lambda 直接放在对 sorted 的调用中：

sortedList = sorted(inputList, key=lambda x: int(x[0]), reverse=True)