Print the key with highest value

Shell Programming and Scripting
1

print the key with highest value

input

a       10
a       20
a       30
b       2
b       3
b       1

output

a       30
b       3
2 
awk '{a[$1]=a[$1]<$2?$2:a[$1]} END {for(i in a) print i,a}'
1 Like
3

Thanx. Can you also modify it so that it can print the max if the value is positive and minimum if the value is negative ?

Fr ex:

a -1
a -2
a -3
b 1
b 2
b 3

a -3
b 3
4 
awk '{if($2<0)a[$1]=a[$1]>$2?$2:a[$1];else a[$1]=a[$1]<$2?$2:a[$1]} END {for(i in a) print i,a}'

or

sort -rg infile | awk '!a[$1]++'
5

Assuming that for a $1 value, all $2 value have the same sign :

awk '{a[$1]=sqrt($2^2)>sqrt(a[$1]^2)?$2:a[$1]}END{for(i in a) print i,a}' infile
6

So then is -4 higher than 3?

awk '$2*$2>A[$1]*A[$1]{A[$1]=$2} END{for(i in A) print i,A}' infile

@huaihuaiz3: that second solution will probably not work reliably. Just try adding an extra space between field 1 and 2 on one of the lines and see what happens to the sort..

7

Is it possible to sum the values instead of taking higher value ?

a -1
a -2
a -3
b 1
b 2
b 3

a -6
b 6
8 
awk '{arr[$1]+=$2} END{for (i in arr) {print i, arr } } ' somefile

Consider reading a book like 'sed/awk' or a tutorial on awk. It is an amazing tool.

Awk - A Tutorial and Introduction - by Bruce Barnett

9

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10

Other parameters may be referenced by sort depend on actual conditions!