Python - Finding and multiplying an integer after specific word

debugcn Published at Dev

Matt

I have a text file that has over 60,000 lines in it and I need to go through and find a specific word and then multiply the number after it. For example:

The cat jumped over the log
  tree 6
the dog also jumped over the log
tree 43

Would end up, if multiplying by 2, as:

The cat jumped over the log
  tree 12
the dog also jumped over the log
tree 86

I know this is fairly simple to do but I can't wrap my head around it. I need to step through the whole text file word by word looking for instances of "tree ", finding the integer after this, making the change, and then replacing the line.

I also know that every occurrence of "tree " will always have an integer next to it.

Thanks for your help.

Edit:

Current code I have as of now is:

file = open('export_desc.txt', 'r')

a = "ext_mpl "
for line in file:
    n = file.find(a+1)
    n = n*2
    file.write(line.replace(a+1, a+n))

file.close()

WKPlus

You don't even have to write a python script, a sed command can help you:

sed -r '/^tree ([0-9]+)$/{h;s/^.* ([0-9]+)$/echo \1*2|bc/e;H;g;s/[0-9]+\n//}' export_desc.txt

Sample:

>sed -r '/^tree ([0-9]+)$/{h;s/^.* ([0-9]+)$/echo \1*2|bc/e;H;g;s/[0-9]+\n//}' 123
The cat jumped over the log
tree 12
the dog also jumped over the log
tree 86
>cat 123
The cat jumped over the log
tree 6
the dog also jumped over the log
tree 43

Collected from the Internet

Please contact [email protected] to delete if infringement.