Extract certain part of a sentence

Hi,

I have the following sentence: CF_PEI_P1_S6

How do I extract the letters before the second _P (the P before number 1)? Keep in mind that any letter as well as the number of letters before this second _P can be subject to change, but must still be able to be extracted.

In this example, the output I want is CF_PEI

An example of a different length sentence could be Teddy_Bear_Cat_P12_S19

I know this can be done with regexp, but I am confused how to generally implement it.

Thank you very much,

Luck

Answer 1

[DGM]

What exactly is the delimiter? Is it:

an instance of '_P1' followed by anything

instr = 'Teddy_Bear_Cat_P12_S19';
prestr = regexp(instr,'.*(?=_P1)','match')

prestr = 1×1 cell array
    {'Teddy_Bear_Cat'}

an instance of '_P' followed by a number

instr = 'Teddy_Bear_Cat_P12_S19';
prestr = regexp(instr,'.*(?=_P[0-9]+)','match')

prestr = 1×1 cell array
    {'Teddy_Bear_Cat'}

an instance of '_P' followed by a number, an underscore, and then another letter-number pattern and then the EOL

instr = 'Teddy_Bear_Cat_P12_S19';
prestr = regexp(instr,'.*(?=_P[0-9]+_S[0-9]+$)','match')

prestr = 1×1 cell array
    {'Teddy_Bear_Cat'}

You can be as explicit as you think you need to be

[Luck Haviland]

Haven't been able to confirm that this actually works, but if it does I will be using the third option. Thank you.