how to change words with the same words but with number at the back bash - bash

Question

I have a file for example with the name file.csv and content
adult,REZ
man,BRB
women,SYO
animal,HIJ
and a line that is nor a directory nor a file
file.csv BRB1 REZ3 SYO2
And what I want to do is change the content of the file with the words that are on the line and then get the nth letter of that word with the number at the end of the those words in capital
and the output should then be
umo
I know that I can get over the line with
for i in "${#:2}"
do
words+=$(echo "$i ")
done
and then the output is
REZ3 BRB1 SYO2

Answer 1

Using awk:
Pass the string of values as an awk variable and then split them into an array a. For each record in file.csv, iterate this array and if the second field of current record matches the first three characters of the current array value, then strip the target character from the first field of the current record and append it to a variable. Print the value of the aggregated variable.
awk -v arr="BRB1 REZ3 SYO2" -F, 'BEGIN{split(arr,a," ")} {for (v in a) { if ($2 == substr(a[v],0,3)) {n=substr(a[v],length(a[v]),1); w=w""substr($1,n,1) }}} END{print w}' file.csv
umo
You can also put this into a script:
#!/bin/bash
words="${2}"
src_file="${1}"
awk -v arr="$words" -F, 'BEGIN{split(arr,a," ")} \
{for (v in a) { \
if ($2 == substr(a[v],0,3)) { \
n=substr(a[v],length(a[v]),1); \
w=w""substr($1,n,1);
}
}
} END{print w}' "$src_file"
Script execution:
./script file.csv "BRB1 REZ3 SYO2"
umo

Answer 2

This is a way using sed.
Create a pattern string from command arguments and convert lines with sed.
#!/bin/bash
file="$1"
pat='s/^/ /;Te;'
for i in ${#:2}; do
pat+=$(echo $i | sed 's#^\([^0-9]*\)\([0-9]*\)$#s/.\\{\2\\}\\(.\\).*,\1$/\\1/;#')
done
pat+='Te;H;:e;${x;s/\n//g;p}'
eval "sed -n '$pat' $file"

Answer 3

Try this code:
#!/bin/bash
declare -A idx_dic
filename="$1"
pattern_string=""
for i in "${#:2}";
do
pattern_words=$(echo "$i" | grep -oE '[A-Z]+')
index=$(echo "$i" | grep -oE '[0-9]+')
pattern_string+=$(echo "$pattern_words|")
idx_dic["$pattern_words"]="$index"
done
pattern_string=${pattern_string%|*}
while IFS= read -r line
do
line_pattern=$(echo $line | grep -oE $pattern_string)
[[ -n $line_pattern ]] && line_index="${idx_dic[$line_pattern]}" && echo $line | awk -v i="$line_index" '{split($0, chars, ""); printf("%s", chars[i]);}'
done < $filename
first find the capital words pattern and catch the index corresponding
then construct the hole pattern words string which connect with |
at last, iterate the every line according to the pattern string, and find the letter by the index
Execute this script.sh like:
bash script.sh file.csv BRB1 REZ3 SYO2