How to sort numbers in ascending order in a csv file made from python

Question

I want to get the scores which the user has to input then order the scores in ascending order however I am struggling to do so. Below is my code so far and it doesn't display the scores in order.Thanks in advance and your help is very much appreciated.

classa = input("what class are you in?")

if classa == "1":

    file=open("class 1.csv", "a+")

if classa == "2":

    file=open("room2.csv", "a+")

if classa == "3":

    file=open("class3.csv", "a+")

score1= int(input("Enter the score 1 results: "))

score2= int(input("Enter the score 2 results: "))

score3= int(input("Enter the score 3 results: "))

newrecord =score1,",",score2,",",score3

file.write(newrecord)

file.write("\n")

file.close()


import csv

import operator

with open('room2.csv','r') as csvfile:

    readCSV = csv.reader(csvfile, delimiter=',')

    for row in readCSV:

        print (row)

If neither 1 2 or 3 are entered your code will error as file won't be defined — Padraic Cunningham, Dec 20 '15 at 19:41
You should find the answer [here](http://stackoverflow.com/questions/2100353/sort-csv-by-column) — iScrE4m, Dec 20 '15 at 19:41
@iScrE4m Thank you, however I got an error which says 'file.write(newrecord) must be str not tuple. — Bob Stanley, Dec 20 '15 at 19:49
@PadraicCunningham the scores, 'score1','score2' and 'score3' — Bob Stanley, Dec 20 '15 at 19:51
Yes but from where, the csv file? And do you mean each row individually? — Padraic Cunningham, Dec 20 '15 at 19:51
@PadraicCunningham Yes, the csv file. The scores added together then sorted from highest to lowest. — Bob Stanley, Dec 20 '15 at 19:51

Padraic Cunningham · Answer 1 · 2015-12-20T20:10:24.810

1

You also cannot write a tuple to the file which is what newrecord = score1,",",score2,",",score is creating. You need to make a string from the scores and write that:

newrecord = "{},{},{}\n".formmat(score1,score2,score3)

file.write(newrecord)

To sort existing scores you just need to call sorted on each row, using int as the key to sorted so you values are compared as integers not strings, set reverse=True to order from highest to lowest.

with open('room2.csv','r') as csvfile:  
    readCSV = csv.reader(csvfile)
    for row in readCSV:
        srt_row = sorted(row,key=int,reverse=True)

To sum each row and then sort, sum the values after mapping to ints again setting reverse=True to sort from high to low:

with open('room2.csv') as csvfile:
    readCSV = csv.reader(csvfile)
    srt = sorted((sum(map(int,row)) for row in readCSV), reverse=True)

If you want to write to a file:

with open('room2.csv','r') as csvfile, open("out.csv","w") as out:
    readCSV = csv.reader(csvfile)
    for scre in sorted((sum(map(int, row)) for row in readCSV), reverse=True):
        out.write(str(scre))

edited Dec 20 '15 at 20:10

answered Dec 20 '15 at 19:52

Padraic Cunningham

176,452
29
245
321

When I run the code I get an error which says 'file.write(newrecord) must be str not tuple'. Do you know how to solve this? – Bob Stanley Dec 20 '15 at 19:57
@BobStanley, if you use the code above there will be no error – Padraic Cunningham Dec 20 '15 at 20:05
Yes thanks for that. However, I am also using parts of my code above which do give me an error and I am still confused on which parts of code I need in order to successfully code this. – Bob Stanley Dec 20 '15 at 20:10
@BobStanley, your error is because you make a tuple and then try to write it to the file, I added how to do it properly – Padraic Cunningham Dec 20 '15 at 20:11
Thanks a lot. Would you know how to add the person's name along side their score, for example, Bob 24, James 20, Paul 18 etc. The program will ask their name at the start. – Bob Stanley Dec 20 '15 at 20:30
Upvoting ya answer just because OP is trying to delete this post :-( – Bhargav Rao Feb 17 '16 at 19:26
@BhargavRao, how do you know? – Padraic Cunningham Feb 17 '16 at 19:27
He's defacing a lot of his posts (See the questions revisions). He's already deleted one other of his post. Also be on vigil for edits on your post http://stackoverflow.com/review/suggested-edits/11305123 – Bhargav Rao Feb 17 '16 at 19:28
@BhargavRao, I am beginning to think Computer Science , Oxford might be a ruse .. :) – Padraic Cunningham Feb 17 '16 at 19:30

Tenzin · Answer 2 · 2015-12-20T19:57:47.487

-1

You could use sort() to sort a list.
For example:

# List 
listOne = ['5', '7', '1']
# Sort the list 
listOne.sort()
# Display the results 
print('List', listOne)

You can eather sort the list before writing the record to a csv file, or when reading the csv file add the values to a list and sort those.

Example 2:
Sort before adding the values to the csv file.

# Declare an empty list 
newrecord = [] 

score1= int(input("Enter the score 1 results: "))
score2= int(input("Enter the score 2 results: "))
score3= int(input("Enter the score 3 results: "))

# Add scores 
newrecord.append(score1)
newrecord.append(score2)
newrecord.append(score3)
# Sort list 
newrecord.sort()
# Print result 
print(newrecord)

Example 3:
Sort the values after taking the values from the csv file.

# Declare an empty list. 
csvList = [] 

with open('room2.csv','r') as csvfile:
    readCSV = csv.reader(csvfile, delimiter=',')
    for row in readCSV:
        # Add value to a list. 
        csvList.append(row)

# Sort the values from the CSV file. 
csvList.sort()

# Print result. 
print(csvList)

edited Dec 20 '15 at 19:57

answered Dec 20 '15 at 19:45

Tenzin

2,415
2
23
36

I want the numbers to saved in a csv file then I read the csv file and sort it in ascending order. – Bob Stanley Dec 20 '15 at 19:50
You could do that as well. Read the CVS file number, store those in a list and then sort that list. – Tenzin Dec 20 '15 at 19:52
Why is my post -1? Topic Starter aks how to sort items, I give a few suggestion and people give me negative feedback and don't tell me why? – Tenzin Dec 20 '15 at 19:58
1

That wasn't me, I can't upvote nor down vote an answer as I haven't reached 15 reputation – Bob Stanley Dec 20 '15 at 20:01
I know. I hope I gave you some clues though. :-)) – Tenzin Dec 20 '15 at 20:02
when I tried to run example 3 the output was just [] – Bob Stanley Dec 20 '15 at 20:05
Not mine but this would error in python3 and fail silently in python3, you are mixing types – Padraic Cunningham Dec 20 '15 at 20:06
I am have tested this code in my python, and it gives no errors. But I did not test the file section. Maybe the file is not being read correctly? – Tenzin Dec 20 '15 at 20:10
@Tenzin, you cannot sort mixed types in python3 as you cannot sort string digits correctly in either python2 or 3. – Padraic Cunningham Dec 20 '15 at 20:12
Then how come Example 1 works in: http://www.tutorialspoint.com/execute_python3_online.php ? – Tenzin Dec 20 '15 at 20:13
@Tenzin, I don't need to check, I can guarantee you it does not work, I suggest you try doing it with numbers with more that 1 digit. Strings are compared lexicographically so single digit strings are not going to tell you much – Padraic Cunningham Dec 20 '15 at 20:15
If you use `sort()` with digits you should add `key=float`, for example: `listOne.sort(key=float)` Then it still will work. I just tested it. – Tenzin Dec 20 '15 at 20:19

How to sort numbers in ascending order in a csv file made from python

2 Answers2

Linked