Find and remove part of a string which precedes a particular substring

Hi, I have cell arrays similar to A

A = {{'all the governments have tended to practice politics of inclusion'}
     {'politics of inclusion are particularly striking in highlighting'}
     {'the ways in which the politics of inclusion are being taken up'}
     ...
     };

and all of them contain the following substring

     'politics of inclusion'

For each of my cell arrays, I would like to detect if there is some text before the substring "politics of inclusion".

If Yes, I would like to remove the text which precedes my substring of interest, i.e. "politics of inclusion", and getting the following output:

B = {{'politics of inclusion'}
     {'politics of inclusion are particularly striking in highlighting'}
     {'politics of inclusion are being taken up'}
     ...
     };

Any idea on how (i) to detect if some text exists before a certain substring and (ii) how to remove it ?

Answer 1

[Steven Lord]

Convert A to a string array then use the string processing functions like extractAfter and eraseBetween.

A = {{'all the governments have tended to practice a politics of inclusion'}
     {'politics of inclusion are particularly striking in highlighting'}
     {'the ways in which the politics of inclusion are being taken up'}
     };
P = 'politics of inclusion';
result = P + extractAfter(string(A), P) % or

result = 3×1 string array
    "politics of inclusion"
    "politics of inclusion are particularly striking in highlighting"
    "politics of inclusion are being taken up"

result2 = eraseBetween(string(A), 1, P)

result2 = 3×1 string array
    "politics of inclusion"
    "politics of inclusion are particularly striking in highlighting"
    "politics of inclusion are being taken up"

[Walter Roberson]

A = {{'all the governments have tended to practice a politics of inclusion'}
     {'politics of inclusion are particularly striking in highlighting'}
     {'the ways in which the politics of inclusion are being taken up'}
     {'grew three sizes that day!'}
     };
P = 'politics of inclusion';
result = P + extractAfter(string(A), P) % or

result = 4×1 string array
    "politics of inclusion"
    "politics of inclusion are particularly striking in highlighting"
    "politics of inclusion are being taken up"
    <missing>

result2 = eraseBetween(string(A), 1, P)

result2 = 4×1 string array
    "politics of inclusion"
    "politics of inclusion are particularly striking in highlighting"
    "politics of inclusion are being taken up"
    "grew three sizes that day!"

The <missing> result is arguably wrong: if there is no pattern match then there should be no erasing going on.

The eraseBetween() works well though.

[Sim]

Many thanks @Steven Lord,

Many thanks @Walter Roberson,

Both your solutions are great to me!

If possible, I would accept both answers!

Answer 2

[Walter Roberson]

A = {{'all the governments have tended to practice politics of inclusion'}
     {'politics of inclusion are particularly striking in highlighting'}
     {'the ways in which the politics of inclusion are being taken up'}
     ...
     };
As = vertcat(A{:});

extractAfter(As, lookAheadBoundary('politics of inclusion'))

ans = 3×1 cell array
    {'politics of inclusion'                                          }
    {'politics of inclusion are particularly striking in highlighting'}
    {'politics of inclusion are being taken up'                       }

[Sim]

Many thanks @Walter Roberson,

Many thanks @Steven Lord,

Both your solutions are great to me!

If possible, I would accept both answers!