python equivalent to sed

Question

Is there a way, without a double loop to accomplish what the following sed command does

Input:

Time Banana spinach turkey 

sed -i "/Banana/ s/$/Toothpaste/" file

Output:

Time BananaToothpaste spinach turkey 

What I have so far is a double list which would take a long time to go through both.

List a has a bunch of numbers list b has a the same bunch of numbers but in a different order

For each entry in A i want to find the line in B with that same number and add value C to the end of it.

Hope this makes sense, even if my example doesn't.

I was doing the following in Bash and it was working however it was super slow...

for line in $(cat DATSRCLN.txt.utf8); do         srch=$(echo $line | awk -F'^' '{print $1}');         rep=$(echo $line | awk -F'^' '{print $2}');         sed -i "/$(echo $srch)/ s/$/^$(echo $rep)/" tmp.1; done 

Thanks!

Answer 1

Using re.sub():

newstring = re.sub('(Banana)', r'\1Toothpaste', oldstring) 

This catches one group (between first parentheses), and replaces it by ITSELF (the \number part) followed by a desired suffix. It is needed to use r'' (raw string) so that the escape is correctly interpreted.