Shell Programming and Scripting

awk '                     # There are two associative arrays, which use the first field as the index L(ow) and H(high)
  NR==1 {                  
    next                  # Skip header
  }

  !($1 in L) {            # For every line, if no array element exist for the first field in array L,
    L[$1]=$2              # then create one with the second field as value. This becomes the Lowest number
  }

  $2<L[$1] {              # If the second field is lower than the array element in L for the first field, 
    L[$1]=$2              # then replace it with the second field as the new lowest number
  } 

  $2>=H[$1] {             # If the second field is higher or equal to the array element in H for the first field,
    H[$1]=$2              # Then replace it with the second field as the new highest number
  }

  END {                   # After the input file has been read
    for(i in L)           # For all elements in array L (which are the unique field values)
      print i, L[i], H[i] # Print the element name (the "operation" ) followed by the low and high values
  }
' FS=, OFS=,  file        # Specify a comma as both input and output field separators and specify the file name

$
$ cat data.txt
Opeation,Time-Taken
operation1,83621
operation2,72321
operation3,13288
operation2,12312
operation1,12321
operation2,45455
operation2,42543
operation1,87934
operation4,94865
operation5,27383
operation6,322
operation6,93483
operation7,3223
$
$ cat -n group_data.sh
     1  #!/usr/bin/bash
     2  header="y"
     3  while read line
     4  do
     5      if [ ! -z "$header" ] ; then
     6          header=
     7          continue
     8      fi
     9      opr=${line%%,*}
    10      if [ -z "$prev_opr" ] ; then
    11          # set min, max if first data line
    12          min=${line##*,}
    13          max=$min
    14      elif [ "$opr" != "$prev_opr" ] ; then
    15          # if opr changes, print previous line and set min, max
    16          echo "$prev_opr,$min,$max"
    17          min=${line##*,}
    18          max=$min
    19      elif [ "${line##*,}" -gt "$min" ] ; then
    20          # if opr is same, set max if needed
    21          max=${line##*,}
    22      fi
    23      prev_opr=$opr
    24  done <<< "$(sort -t, -k1,1 -k2,2n data.txt)"
    25  echo "$prev_opr,$min,$max"
    26
$
$ ./group_data.sh
operation1,12321,87934
operation2,12312,72321
operation3,13288,13288
operation4,94865,94865
operation5,27383,27383
operation6,322,93483
operation7,3223,3223
$
$

while IFS=, read operation value

#!/usr/bin/env bash

# @(#) s2       Demonstrate statistics for grouped data, datamash.

# Utility functions: print-as-echo, print-line-with-visual-space, debug.
# export PATH="/usr/local/bin:/usr/bin:/bin"
LC_ALL=C ; LANG=C ; export LC_ALL LANG
pe() { for _i;do printf "%s" "$_i";done; printf "\n"; }
pl() { pe;pe "-----" ;pe "$*"; }
em() { pe "$*" >&2 ; }
db() { ( printf " db, ";for _i;do printf "%s" "$_i";done;printf "\n" ) >&2 ; }
db() { : ; }
C=$HOME/bin/context && [ -f $C ] && $C datamash dixf

FILE=${1-data2}
E=expected-output.txt

pl " Input data file $FILE:"
cat $FILE

pl " Expected output:"
cat $E

pl " Results:"
datamash -t',' --header-in --sort --group=1 min 2 max 2 < $FILE |
tee f1

pl " Verify results if possible:"
C=$HOME/bin/pass-fail
[ -f $C ] && $C || ( pe; pe " Results cannot be verified." ) >&2

pl " Results for producing header on output:"
# datamash -t',' --header-in --header-out --sort --group=1 min 2 # max 2 < $FILE
datamash -t',' -H --sort --group=1 min 2 max 2 < $FILE

pl " Details for datamash:"
dixf datamash

exit 0

$ ./s2

Environment: LC_ALL = C, LANG = C
(Versions displayed with local utility "version")
OS, ker|rel, machine: Linux, 3.16.0-4-amd64, x86_64
Distribution        : Debian 8.7 (jessie) 
bash GNU bash 4.3.30
datamash (GNU datamash) 1.0.6
dixf (local) 1.42

-----
 Input data file data2:
Opeation,Time-Taken
operation1,83621
operation2,72321
operation3,13288
operation2,12312
operation1,12321
operation2,45455
operation2,42543
operation1,87934
operation4,94865
operation5,27383
operation6,322
operation6,93483
operation7,3223

-----
 Expected output:
operation1,12321,87934
operation2,12312,72321
operation3,13288,13288
operation4,94865,94865
operation5,27383,27383
operation6,322,93483
operation7,3223,3223

-----
 Results:
operation1,12321,87934
operation2,12312,72321
operation3,13288,13288
operation4,94865,94865
operation5,27383,27383
operation6,322,93483
operation7,3223,3223

-----
 Verify results if possible:

-----
 Comparison of 7 created lines with 7 lines of desired results:
 Succeeded -- files (computed) f1 and (standard) expected-output.txt have same content.

-----
 Results for producing header on output:
GroupBy(Opeation),min(Time-Taken),max(Time-Taken)
operation1,12321,87934
operation2,12312,72321
operation3,13288,13288
operation4,94865,94865
operation5,27383,27383
operation6,322,93483
operation7,3223,3223

datamash        command-line calculations (man)
Path    : /usr/bin/datamash
Version : 1.0.6
Type    : ELF 64-bit LSB executable, x86-64, version 1 (SYSV ...)
Help    : probably available with -h,--help
Repo    : Debian 8.7 (jessie) 
Home    : http://www.gnu.org/software/datamash

${line##*,}

 while ((c = getchar()) != EOF) {