MATLAB: How to find and remove the rows starting with different word

cell arrayMATLAB

Hi All;

I have a 40000 row document. The words 1 to 485 start with the letter "a". The words 486 to 1158 start with the letter "b". It starts with the letter "c" between 1158 and 4000… There are some erroneous places among these word groups. For example, there are words starting with another letter such as "b, c, d, v …" in groups of words that should start with the letter "a" between 1 and 485. How can I find and remove the rows of these?

Thank you for your help.

Best Answer

I hope this helps.

Cnew = cellfun(@char,Cnew,'uni',0); % convert the cell array contents to string
index = cellfun('isempty',(regexpi(Cnew,'^c.*'))); % find index of line not starting with C
Cnew(index) = []; % remove line not starting with C

Related Solutions

MATLAB: Find index of cells containing a string

The problem is not with your search expression, which works fine, but the fact that the exact string 'CERT' is not present in your cell array.

>>double(s{7, 2})
ans = 
    67    69    82    84   160   160

Notice the two 160 characters at the end of the string ([67 69 82 84] are the character codes for CERT). In my version of matlab, char(160) renders as a blank space (depending on your locale it may render differently).

In fact, if you look through your whole matrix, there are a fair number of strings where the character 160 appears. It seems that it's the only character outside the ASCII range, as well:

cellfun(@(s) double(s(s>127)), text, 'UniformOutput', false) %show characters outside ASCII

Probably, the simplest thing is to remove these characters (which I assume you did not want in the first place):

text = cellfun(@(s) s(s<128), text, 'UniformOutput', false);

Your search expression will then work:

>>[row, col] = find(cellfun(@(s) strcmp(s, 'CERT'), text))
row =
   7
col =
   2

MATLAB: Selecting random part of string

Max - use randperm to generate a random index into your character array. Try the following

 alphabet = 'abcdefghijklmnopqrstuvwxyz';
 randIdx  = randperm(length(alphabet),1); % generate the random index into array
 randChar = alphabet(randIdx);            % get the random character
 alphabet(randIdx) = [];                  % remove the character

For example, if

 randIdx =
    14

then

 randChar =
     n

and

 alphabet =
     abcdefghijklmopqrstuvwxyz

with the 'n' removed.

Best Answer

Related Solutions

MATLAB: Find index of cells containing a string

MATLAB: Selecting random part of string

Related Question