Grade Calculation Script

Purpose

calculate total and adjusted scores from a text file with scores in columns: number, position, and width of input file columns may vary
example input file: NAME SID4 Q1 Q2 Q3 Q4 E1 Q5 Q6 Q7 Q8 E2 Q9 QA QB QC P1 Doe, Jane 1234 8 9 7 10 42 9 10 7 9 45 8 9 9 40
example output file: NAME SID4 Q1 Q2 Q3 Q4 E1 Q5 Q6 Q7 Q8 E2 Q9 QA QB QC P1 TOT ADJ Doe, Jane 1234 8 9 7 10 42 9 10 7 9 45 8 9 9 40 222 192

Code

while read Line ; do
  [[ $Line == '' || $Line == \#* ]] && echo "$Line" && continue
  echo "$Line TOT ADJ"
  Length=${#Line}
  First=(0)
  for (( Ix=1 ; Ix < ${#Line} ; ++Ix )) ; do
    [[ ${Line:$Ix:1} != ' ' && ${Line:$Ix-1:1} == ' ' ]] && First+=($Ix) ; done
  for Col in ${!First[@]} ; do
    (( $Col == ${#First[@]} - 1 )) && End=${#Line} || End=${First[$Col+1]}
    Head+=("${Line:${First[$Col]}:$(( $End-${First[$Col]} ))}") ; done
  break ; done

while read Line ; do
  [[ $Line == '' || $Line == \#* ]] && echo "$Line" && continue
  Data=()
  for Col in ${!First[@]} ; do
    (( $Col == ${#First[@]} - 1 )) && End=${#Line} || End=${First[$Col+1]}
    Data+=("${Line:${First[$Col]}:$(( $End-${First[$Col]} ))}") ; done
  Quiz=() ; ExPr=()
  for Field in ${!Head[@]} ; do
    [[ ${Head[Field]} == Q[0-9A-F]* ]] && Quiz+=($(( ${Data[Field]}+0 )))
    [[ ${Head[Field]} == [EP][0-9]* ]] && ExPr+=($(( ${Data[Field]}+0 ))) ; done
  Quiz=($(printf "%d\n" ${Quiz[@]} | sort -n))
  LowQuiz=$(( ${Quiz[0]}+${Quiz[1]}+${Quiz[2]}+${Quiz[3]}+${Quiz[4]} ))
  ExPr=($(printf "%s\n" "${ExPr[@]}" | sort -n))
  LowExPr=${ExPr[0]}
  (( $LowQuiz < $LowExPr )) && Drop=$LowQuiz || Drop=$LowExPr
  Tot=0
  for Qnum in ${!Quiz[@]} ; do
    (( Tot+=${Quiz[Qnum]} )) ; done
  for Enum in ${!ExPr[@]} ; do
    (( Tot+=${ExPr[Enum]} )) ; done
  Adj=$(( $Tot - $Drop ))
  printf "%-${Length}s%4s%4s\n" "$Line" "$Tot" "$Adj" ; done

Explanation

The first section reads the header line and finds the character positions of the start of each heading.
while read Line ; do: read header line and any preceding blank or comment (begin with #) lines
[[ $Line == '' || $Line == \#* ]] && echo "$Line" && continue: if line is blank or begins with # then print it and continue to next iteration
echo "$Line TOT ADJ": print header line with 2 more fields for total and adjusted total
Length=${#Line}: save length of header line for subsequent output
First=(0): array for positions of the first char in each field, 1st element 0
for (( Ix=1 ; Ix < ${#Line} ; ++Ix )) ; do: loop over each character in header line (Ix is index)
[[ ${Line:$Ix:1} != ' ' && ${Line:$Ix-1:1} == ' ' ]] && First+=($Ix) ; done: if char at Ix is not space and char at previous Ix is space then append Ix to First array
for Col in ${!First[@]} ; do: loop over indexes in First
(( $Col == ${#First[@]} - 1 )) && End=${#Line} || End=${First[$Col+1]}: if last columm then end of column is last char of Line else end of column is first char of next column
Head+=("${Line:${First[$Col]}:$(( $End-${First[$Col]} ))}") ; done: append appropriate substring (start index, count) of Line to array of headings
break ; done: header processing finished, exit loop
The second section reads the data lines, divides them into fields defined by the character positions in the header, and calculates totals of fields which have headings matching quizzes, exams, or programs.
while read Line ; do: read data lines and any blank or comment lines
[[ $Line == '' || $Line == \#* ]] && echo "$Line" && continue: if line is blank or begins with # then print it and continue to next iteration
Data=(): initialize array of scores for each iteration
for Col in ${!First[@]} ; do: loop over indexes in First
(( $Col == ${#First[@]} - 1 )) && End=${#Line} || End=${First[$Col+1]}: if last columm then end of column is last char of Line else end of column is first char of next column
Data+=("${Line:${First[$Col]}:$(( $End-${First[$Col]} ))}") ; done: append appropriate substring (start index, count) of Line to array of scores
Quiz=() ; ExPr=(): initialize arrays of quiz scores and exam/program scores for each iteration
for Field in ${!Head[@]} ; do: loop over indexes in header array
[[ ${Head[Field]} == Q[0-9A-F]* ]] && Quiz+=($(( ${Data[Field]}+0 ))): if heading matches quiz then append corresponding data to quiz array (add 0 to make it numeric)
[[ ${Head[Field]} == [EP][0-9]* ]] && ExPr+=($(( ${Data[Field]}+0 ))) ; done: if heading matches exam/program then append corresponding data to exam/program array
Quiz=($(printf "%d\n" ${Quiz[@]} | sort -n)): output values separated with newlines, pipe to sort, assign back to quiz array
LowQuiz=$(( ${Quiz[0]}+${Quiz[1]}+${Quiz[2]}+${Quiz[3]}+${Quiz[4]} )): add 5 lowest quiz scores (this is simpler than a loop)
ExPr=($(printf "%s\n" "${ExPr[@]}" | sort -n)): output values separated with newlines, pipe to sort, assign back to exam/program array
LowExPr=${ExPr[0]}: lowest exam/program score
(( $LowQuiz < $LowExPr )) && Drop=$LowQuiz || Drop=$LowExPr: set score(s) to drop to smaller of quizzes or exam/program
Tot=0: initialize total score for each iteration
for Qnum in ${!Quiz[@]} ; do: loop over indexes in quiz score array
(( Tot+=${Quiz[Qnum]} )) ; done: add current score to total
for Enum in ${!ExPr[@]} ; do: loop over indexes in exam/program score array
(( Tot+=${ExPr[Enum]} )) ; done: add current score to total
Adj=$(( $Tot - $Drop )): subtract dropped score(s) from total
printf "%-${Length}s%4s%4s\n" "$Line" "$Tot" "$Adj" ; done: print Line in field matching header, then total and adjusted fields

Notes

programming style: && and || are used instead of simple if statements to reduce the number of lines; simple related commands are combined on single lines to reduce the number of lines; blank lines and spaces are added for readability
performance: the only external program this program calls is sort; re-implementing sort in bash would not be worth the trouble; finding the 5 lowest quiz scores without sorting would not be worth the trouble
limitations: this program uses bash extensions and will not run on simpler shells; this program won't handle improperly formatted input lines