在2D清单上排序

Question

I have a 2D list that I have created from reading in a txt file. I have written this code to sort the list by the highest value - position 5.

sort = list(sorted(sort,key=lambda x: x[5],reverse=True))
for i in range( 0, len( sort ) ):
            print( "Name:",sort[i][0],"\tscore1:",sort[i][1],"\tscore2:",sort[i][2],"\tscore3:",sort[i][3], "\tHighest:",sort[i][5] )

The code seems to work apart from that for some reason it put's 10 (the only 2 digit number at the bottom of the list rather than at the top. I have use the max function to attain the highest number and then simply appended it to the end of each list.

Name: B score1: 6 score2: 1 score3: 3 Highest: 6

Name: Z score1: 4 score2: 4 score3: 5 Highest: 5

Name: Neil score1: 4 score2: 1 score3: 3 Highest: 4

Name: fred score1: 10 score2: 0 score3: 0 Highest: 10

Any help appreciated.

Answer 1

The problem is almost certainly that you don't actually have numbers, but strings.*

Strings are compared lexicographically—that is, alphabetical order, character by character, the same way you'd sort words in a dictionary. Digits aren't anything special; they're treated just like any other character. So, "10" is smaller than "2" because the first character of the first string, "1" , is smaller than the first string of the second character, "2" .

What you probably want to do is store integers (or floats, or some other numeric type) in the first place.

But if you want to store strings and sort by their integer value, you can pass int as the sorting key. Or, in your case, lambda x: int(x[5]) instead of lambda x: x[5] .

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_{* For debugging in the future: when you just print a value, it can be ambiguous what it is. The number 2 and the string "2" both just print out as 2 . It can help to temporarily print(repr(x)) and/or print(type(x)) to find problems like this. (You'd get 2 vs. '2' and int vs. str , respectively.) Even the repr can still occasionally be ambiguous—but this mostly only happens in cases where it usually doesn't matter. Mostly.}

Answer 2

This is because x[5] seems to be a string. You should try converting it to an int by calling int(x[5]) .