Bash: sort text file by last field value

awksedsorting

I have a text file containing ~300k rows. Each row has a varying number of comma-delimited fields, the last of which is guaranteed numerical. I want to sort the file by this last numerical field. I can't do:

sort -t, -n -k 2 file.in > file.out

as the number of fields in each row is not constant. I think sed, awk maybe the answer, but not sure how. E.g:

awk -F, '{print $NF}' file.in

gives me the last column value, but how to use this to sort the file?

Best Answer

Use awk to put the numeric key up front. $NF is the last field of the current record. Sort. Use sed to remove the duplicate key.

awk -F, '{ print $NF, $0 }' yourfile | sort -n -k1 | sed 's/^[0-9][0-9]* //'

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C# – How to sort a dictionary by value

Use LINQ:

Dictionary<string, int> myDict = new Dictionary<string, int>();
myDict.Add("one", 1);
myDict.Add("four", 4);
myDict.Add("two", 2);
myDict.Add("three", 3);

var sortedDict = from entry in myDict orderby entry.Value ascending select entry;

This would also allow for great flexibility in that you can select the top 10, 20 10%, etc. Or if you are using your word frequency index for type-ahead, you could also include StartsWith clause as well.

Python – How to sort a list of dictionaries by a value of the dictionary

The sorted() function takes a key= parameter

newlist = sorted(list_to_be_sorted, key=lambda d: d['name'])

Alternatively, you can use operator.itemgetter instead of defining the function yourself

from operator import itemgetter
newlist = sorted(list_to_be_sorted, key=itemgetter('name'))

For completeness, add reverse=True to sort in descending order

newlist = sorted(list_to_be_sorted, key=itemgetter('name'), reverse=True)

Best Answer

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C# – How to sort a dictionary by value

Python – How to sort a list of dictionaries by a value of the dictionary

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