replace values in an array based on previous values

Hello everyone!!

I have a dataset with two columns.

1. TEL_TYPE which take values 'P','A','D','N'
2. PORT_FLAG which take values 'N','S'.

I have the below sequence which being repeated (not with steady number of 'P' in the middle)

TEL_TYPE : A P P P P D

PORT_FLAG : N N N S N N

I want to find when the PORT_FLAG='S' and then the PORT_FLAG where TEL_TYPE='D' to have the value 'S' so in the above example the result will be:

TEL_TYPE : A P P P P D

PORT_FLAG : N N N S N s

How can I achieve this? Thank you!

Vanessa

[Adam]

What is the purpose of finding the PORT_FLAG == 'S'? Are there occurrences of 'D' in TEL_TYPE that you don't want to change PORT_FLAG to 'S' for?

Answer 1

[Image Analyst]

Here's one way, assuming they're character arrays:

TEL_TYPE  = ['A' 'P' 'P' 'P' 'P' 'D' 'P' 'D' 'P' 'P']
PORT_FLAG = ['N' 'N' 'N' 'S' 'N' 'N' 'S' 'N' 'N' 'S']
% Find 'S's
sLocations = find(PORT_FLAG == 'S')
for k = 1 : length(sLocations)
  index = sLocations(k);
  firstDLocation = index + find(TEL_TYPE(index:end) == 'D', 1, 'first') - 1
  if ~isempty(firstDLocation)
    PORT_FLAG(firstDLocation) = 's'
  end
end
PORT_FLAG % Display in command window.

Note I lengthened the arrays to make sure it worked for not only the first instance of S.

[Vanessa]

Thank you very much!!