Expand one column while preserving another - text

Question

I am trying to get column one repeated for every value in column two which needs to be on a new line.
cat ToExpand.txt
Pete horse;cat;dog
Claire car
John house;garden
My first attempt:
cat expand.awk
BEGIN {
FS="\t"
RS=";"
}
{
print $1 "\t" $2
}
awk -f expand.awk ToExpand.txt
Pete horse
cat
dog
Claire car
John
garden
The desired output is:
Pete horse
Pete cat
Pete dog
Claire car
John house
John garden
Am I on the right track here or would you use another approach? Thanks in advance.

Answer 1

You could also change the FS value into a regex and do something like this:
awk -F"\t|;" -v OFS="\t" '{for(i=2;i<=NF;i++) print $1, $i}' ToExpand.txt
Pete horse
Pete cat
Pete dog
Claire car
John house
John garden
I'm assuming that:
The first tab is the delimiter for the name
There's only one tab delimiter - If tab delimited data occurs after the ; section use fedorqui's implementation.
It's using an alternate form of setting the OFS value ( using the -v flag ) and loops over the fields after the first to print the expected output.
You can think of RS in your example as making "lines" out of your data ( records really ) and your print block is acting on those "lines"(records) instead of the normal newline. Then each record is further parsed by your FS. That's why you get the output from your first attempt. You can explore that by printing out the value of NF in your example.

Answer 2

Try:
awk '{gsub(/;/,ORS $1 OFS)}1' OFS='\t' file
This replaces every occurrence of a semicolon with a newline, the first field and the output field separator..
Output:
Pete horse
Pete cat
Pete dog
Claire car
John house
John garden