Create an array from another and find the indices.

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João
João 2014-2-11
评论： Jos (10584) 2014-2-11
Hi everyone,
I have an array with variables like S,SV, V etc now I want to create a new array only with the V variable so for example;
V
SV
S
V
will become
V
V
after this I need to know the indices where I found each one of the V variables, so in this example I should get Indices = 1 and 4
Thank you for the help.
  2 个评论
Walter Roberson
Walter Roberson 2014-2-11
Are those strings, or are they numeric values? If they are numeric values, are they scalars or vectors or arrays? If they are vectors or arrays are all of them the same size?
João
João 2014-2-11
Thx for answering. This is an array of strings I already tried to use an if cycle like this;
%most_common_string
for i=1:744;
if most_common_string{i} == 'V'
periodo=most_common_string{i};
end
end
but instead of getting a new array I'm getting only a cell.

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采纳的回答

Jos (10584)
Jos (10584) 2014-2-11
MySet = {'S' 'V' 'SV' 'S' 'V' 'V' 'S' 'SV' 'V'}
MyStr = 'V'
tf = strcmp(MySet, MyStr)
index = find(tf)
KeepSet1 = MySet(tf)
KeepSet2 = repmat(MyStr,1,numel(index)) % same result
  2 个评论
João
João 2014-2-11
编辑：João 2014-2-11
Thank you Jos, KeepSet1 is giving me all the V's but KeepSet2 is giving me an array only with VVVVVVVVVV(...) so for that I used
ind = cellfun(@(s) strcmp(s,'V'), most_common_string)
find(ind)
Jos (10584)
Jos (10584) 2014-2-11
Oh, I made a small mistake. I just wanted to point out that what you want to keep are only the V's. There are numel(index) elements to keep. These elements can be retrieved from MySet using the Index OR by repeating the element a number of times. The correct code, however, is:
KeepSet2 = repmat({MyStr},1,numel(index)) % between { }

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更多回答（2 个）

Walter Roberson
Walter Roberson 2014-2-11
find( ismember('V', most_common_string))
  1 个评论
João
João 2014-2-11
Thanks for answering Walter, but when I use find I only get one index, the first index.
Maybe I was not clear, I will need to use those indices later so maybe the best is to get an array with each one of the indices values.

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David Sanchez
David Sanchez 2014-2-11
most_common_string = {'V','SV','S','V','S'};
wanted_string='V';
idx = getnameidx(most_common_string,wanted_string);
idx = find(most_common_string==wanted_string);
k=1;
for i=1:numel(most_common_string)
if most_common_string{i} == 'V'
periodo(k)=i;
k = k+1;
end
end
periodo =
1 4
new_string_array = most_common_string(periodo);
new_string_array =
'V' 'V'
  1 个评论
João
João 2014-2-11
Thanks for your help but I'm getting this error
??? Undefined function or method 'eq' for input arguments of type 'cell'.
Error in ==> Untitled at 110
idx = find(M==wanted_string);
if true
% code
end

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