apply dictionary mapping to the column of a file with awk - bash

Question

I have a text file file.txt with several columns (tab separated), and the first column can contain indexes such as 1, 2, and 3. I want to update the first column so that 1 becomes "one", 2 becomes "two", and 3 becomes "three". I created a bash file a.sh containing:
declare -A DICO=( [1]="one" [2]="two" [3]="three" )
awk '{ $1 = ${DICO[$1]}; print }'
But now when I run cat file.txt | ./a.sh I get:
awk: cmd. line:1: { $1 = ${DICO[$1]}; print }
awk: cmd. line:1: ^ syntax error
I'm not able to fix the syntax. Any ideas? Also there is maybe a better way to do this with bash, but I could not think of another simple approach.
For instance, if the input is a file containing:
2 xxx
2 yyy
1 zzz
3 000
4 bla
The expected output would be:
two xxx
two yyy
one zzz
three 000
UNKNOWN bla

Answer 1

EDIT: Since OP had now added samples so changed solution as per that now.
awk 'BEGIN{split("one,two,three",array,",")} {$1=$1 in array?array[$1]:"UNKONW"} 1' OFS="\t" Input_file
Explanation: Adding explanation for above code too now.
awk '
BEGIN{ ##Starting BEGIN block of awk code here.
split("one,two,three",array,",") ##Creating an array named array whose values are string one two three with delimiter as comma.
}
{
$1=$1 in array?array[$1]:"UNKOWN" ##Re-creating first column which will be if $1 comes in array then its value will be aray[$1] else it will be UNKOWN string.
}
1 ##Mentioning 1 here. awk works on method of condition then action, so making condition is TRUE here and not mentioning any action so by default print of current line will happen.
' Input_file ##mentioning Input_file name here.
Since you haven't shown samples so couldn't tested completely, could you please try following and let me know if this helps.
awk 'function check(value){gsub(value,array[value],$1)} BEGIN{split("one,two,three",array,",")} check(1) check(2) check(3); 1' Input_file
Adding a non-one liner form of solution too here.
awk '
function check(value){
gsub(value,array[value],$1)
}
BEGIN{
split("one,two,three",array,",")
}
check(1)
check(2)
check(3);
1' OFS="\t" Input_file
Tested code as follows too:
Let's say we have following Input_file:
cat Input_file
1213121312111122243434onetwothree wguwvrwvrwvbvrwvrvr
vkewjvrkmvr13232424
Then after running the code following will be the output:
onetwoonethreeonetwoonethreeonetwooneoneoneonetwotwotwo4three4three4onetwothree wguwvrwvrwvbvrwvrvr
vkewjvrkmvronethreetwothreetwo4two4

Answer 2

Given a dico file containing this:
$ cat dico
1 one
2 two
3 three
You could use this awk script:
awk 'NR==FNR{a[$1]=$2;next}($1 in a){$1=a[$1]}1' dico file.txt
This fills the array a with the content of the dico file and replaces the first element of the file.txt file if this one is part of the array.