Most repeated string based on two arguments strings csv file. BASH - bash

Question

First exercise with bash, this is taking a lot of time...
I'm trying to create a script where, giving 2 arguments (height,weight) on athletes.csv returns number of coincidence on both values and predominant nationality based on that. And if that was not enough, if predominance is equal for 2 countries, then echo predominance with lowest id.
Also i can't use awk, grep, sed or csvkit.
Here is csv header:
id,name,nationality,sex,date_of_birth,height,weight,sport,gold,silver,bronze,info
736041664,A Jesus Garcia,ESP,male,1969-10-17,1.72,64,athletics,0,0,0,
532037425,A Lam Shin,KOR,female,1986-09-23,1.68,56,fencing,0,0,0,
435962603,Aaron Brown,CAN,male,1992-05-27,1.98,79,athletics,0,0,1,
521041435,Aaron Cook,MDA,male,1991-01-02,1.83,80,taekwondo,0,0,0,
33922579,Aaron Gate,NZL,male,1990-11-26,1.81,71,cycling,0,0,0,
173071782,Aaron Royle,AUS,male,1990-01-26,1.80,67,triathlon,0,0,0,
266237702,Aaron Russell,USA,male,1993-06-04,2.05,98,volleyball,0,0,1,
Until now:
count=0
while IFS=, read -a id _ nation _ _ height weight _ _ _ _; do
if (( $height == "$2" )) && (( "$weight" == $3 )) ; then
((count++))
fi
done < athletes.csv
echo "$count"
I have seen a similiar problem. But can't find the way to return the most common nationality (strings).
Looking for something similar to:
Count, Predominant_nationality 1.85 130
8460, BRA
Should i try to work the hole exercise with arrays instead trying with lopps? Probably i could do it indexes, but looks like arrays are 1d here?
Any help would be a blessing

Answer 1

It's a problem of sorting and counting that can be resolved with Linux standard text utilities
csv='athletes.csv'
crit='1\.85,90'
echo "Count Predominant_nationality $crit"
# Get fields from csv and sort on filtered fields 2,3
cut -d ',' -f 1,3,6,7 "$csv" | grep "$crit" | sort -t ',' -k2,3 | tr ',' ' ' | \
# Count unique skipping first field, get first
uniq -f 1 -c | sort -n -k1,1nr -k2n | head -n1 | tr -s ' ' | \
# print result
cut -d ' ' -f 2,4 --output-delimiter=' '
Result
Count Predominant_nationality 1.85,90
2 BRA

Answer 2

A few issues with current code:
read -a says to read values into an array but what you really want is to read the values into individual variables
read -r is typical in this type of scenario (-r disables backslashes as escapes)
the if (( ... )) constucts are typically used for integer comparisons and since heights are non-integer (eg, 1.85) it's probably best to stick with string comparisons (especially since we're only interested in equality matches)
Setup; instead of downloading the link/data file I'll add 4x bogus lines to OP's sample input, making sure all 4x lines match OP's sample search parameters (1.85 and 130):
$ cat athletes.csv
id,name,nationality,sex,date_of_birth,height,weight,sport,gold,silver,bronze,info
736041664,A Jesus Garcia,ESP,male,1969-10-17,1.72,64,athletics,0,0,0,
532037425,A Lam Shin,KOR,female,1986-09-23,1.68,56,fencing,0,0,0,
435962603,Aaron Brown,CAN,male,1992-05-27,1.98,79,athletics,0,0,1,
521041435,Aaron Cook,MDA,male,1991-01-02,1.83,80,taekwondo,0,0,0,
33922579,Aaron Gate,NZL,male,1990-11-26,1.81,71,cycling,0,0,0,
173071782,Aaron Royle,AUS,male,1990-01-26,1.80,67,triathlon,0,0,0,
266237702,Aaron Russell,USA,male,1993-06-04,2.05,98,volleyball,0,0,1,
134,Aaron XX1,USA,male,1993-06-04,1.85,130,volleyball,0,0,1,
127,Aaron XX2,CAD,male,1993-06-04,1.85,130,volleyball,0,0,1,
34,Aaron XX3,USA,male,1993-06-04,1.85,130,volleyball,0,0,1,
27,Aaron XX4,CAD,male,1993-06-04,1.85,130,volleyball,0,0,1,
One bash idea:
arg1="1.85"
arg2="130"
maxid=99999999999
unset counts ids maxcount
declare -A counts ids
maxcount=0
while IFS=, read -r id _ nation _ _ height weight _
do
if [[ "${height}" == "${arg1}" && "${weight}" == "${arg2}" ]]
then
(( counts[${nation}]++ ))
# keep track of overall max count
[[ "${counts[${nation}]}" -gt "${maxcount}" ]] && maxcount="${counts[${nation}]}"
# keep track of min(id) for each nation
[[ "${id}" -lt "${ids[${nation}]:-${maxid}}" ]] && ids[${nation}]="${id}"
fi
done < athletes.csv
Alternatively, since it looks like our search patterns are together and can only occur in one location within a line, we can use grep to filter out only the matching rows:
$ grep ",${arg1},${arg2}," athletes.csv
134,Aaron XX1,USA,male,1993-06-04,1.85,130,volleyball,0,0,1,
127,Aaron XX2,CAD,male,1993-06-04,1.85,130,volleyball,0,0,1,
34,Aaron XX3,USA,male,1993-06-04,1.85,130,volleyball,0,0,1,
27,Aaron XX4,CAD,male,1993-06-04,1.85,130,volleyball,0,0,1,
We can then feed this result to the while/read loop and eliminte the need to test the height/weight variables, eg:
while IFS=, read -r id _ nation _
do
(( counts[${nation}]++ ))
[[ "${counts[${nation}]}" -gt "${maxcount}" ]] && maxcount="${counts[${nation}]}"
[[ "${id}" -lt "${ids[${nation}]:-${maxid}}" ]] && ids[${nation}]="${id}"
done < <(grep ",${arg1},${arg2}," athletes.csv)
At this point both of these while/read loops produce:
$ typeset -p counts ids maxcount
declare -A counts=([USA]="2" [CAD]="2" )
declare -A ids=([USA]="34" [CAD]="27" )
declare -- maxcount="2"
From here OP can loop through the list of nations ("${!counts[#]}") looking for counts that are equal to maxcount and when found then apply an additional check to see if the nation has the lowest id (ids[]) seen so far in the loop. At the end of the loop OP should have the country a) count that is equal to maxcount and b) with the lowest id.