Python unusual file sorting

I have a txt file that contains data in the following fashion: ``` 23 1 65 15 19.2 19 2 66 25 25.7 10 3 67 35 16.5 100 4 68 45 10.4 20 5 69 55 6.8 201 6 64 65 9.2 ``` Within the file, each value is separated from other using \t and then \n for next line. I want to sort this file based on the first values of the each line. My expected output is : ``` 10 3 67 35 16.5 19 2 66 25 25.7 20 5 69 55 6.8 23 1 65 15 19.2 100 4 68 45 10.4 201 6 64 65 9.2 ``` But the actual output I am getting is as: ``` 10 3 67 35 16.5 100 4 68 45 10.4 19 2 66 25 25.7 20 5 69 55 6.8 201 6 64 65 9.2 23 1 65 15 19.2 ``` Its taking the values as strings and hence not taking the entire numbers value as integer. I tried parsing, but its not working. My code: ``` with open('filename.txt') as fin: lines = [line.split() for line in fin] lines.sort(key=itemgetter(0),reverse=True) with open('newfile.txt', 'w') as fout: for i in lines: fout.write('{0}\t\t\t\t\n'.format('\t\t\t '.join(i))) ``` Please help if possible.