Using strcmp on multiple strings to get a logical array
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I want to check for the occurrence of 3 possible events in a series of events..
Event = ['a1','b1','a1','c1','b1']';
Check = {'a1','b1','c1'}';
LogA(:,1) = strcmp(Event,Check{1});
LogA(:,2) = strcmp(Event,Check{2});
LogA(:,3) = strcmp(Event,Check{3});
This gives me a 5x3 logical array, but is there a way to do it without calling each column individually? i.e., what if I had 100 strings I wanted to check for and the goal was to have a 5x100 logical array? I don't want to use a "for-loop". I'm assuming there is some matrix way to do this.
1 个评论
Jan
2017-1-15
Note:
Event = ['a1','b1','a1','c1','b1']';
is the same as:
Event = ('a1b1a1c1b1').';
Most likely you mean a cell string instead.
采纳的回答
Kirby Fears
2017-1-12
编辑：Kirby Fears
2017-1-12
There's really nothing wrong with a for loop in this case. However, cellfun is probably what you're looking for:
Event = {'a1','b1','a1','c1','b1'}';
Check = {'a1','b1','c1'}';
l = cellfun(@(c)strcmp(c,Event),Check,'UniformOutput',false);
This produces a cell array the size of Check with logical arrays the size of Event.
You can index like this:
l{index1}(index2)
2 个评论
Also simple to convert to a logical array:
>> Event = {'a1','b1','a1','c1','b1'};
>> Check = {'a1','b1','c1'};
>> X = cellfun(@(c)strcmp(c,Event),Check,'UniformOutput',false);
>> vertcat(X{:})
ans =
1 0 1 0 0
0 1 0 0 1
0 0 0 1 0
Jan
2017-1-15
编辑：James Tursa
2017-1-16
strcmp does not accept: strcmp(Event, Check.') and this does not work also:
bsxfun(@strcmp, Event, Check.') % ERROR!
What a pity.
更多回答（2 个）
Another option which may or may not be faster than cellfun(...):
Event = {'a1','b1','a1','c1','b1'}';
Check = {'a1','b1','c1'}';
LogA = false(numel(Event), numel(Check));
[~, loc] = ismember(Event, Check);
LogA(sub2ind(size(LogA), 1:numel(Event), loc.')) = true
John BG
2017-1-13
Marc
1.
If all 2nd halves of the strings contained in Event is '1', it is reasonable to ignore the entire column:
Event = ['a1';'b1';'a1';'c1';'b1'];
Event_num=double(Event)
=
97 49
98 49
97 49
99 49
98 49
E=Event_num(:,1)';
E =
97 98 97 99 98
2.
Same applies to Checks
Check = ['a1';'b1';'c1'];
Check_num=double(Check)
=
97 49
98 49
99 49
C=Check_num(:,1)';
C =
97 98 99
3.
Occurence of events are listed in variable occ
[Lie,occ]=ismember(E,C)
Lie =
1 1 1 1 1
occ =
1 2 1 3 2
4.
check
Check(occ)
=
abacb
meaning occ contains the occurrences: a1 b1 a1 c1 b1
if you find these lines useful would you please mark my answer as Accepted Answer?
To any other reader, if you find this answer of any help please click on the thumbs-up vote link,
thanks in advance for time and attention
John BG
5 个评论
Jan
2017-1-13
There is no advantage in converting the strings to doubles, because ismember works on CHAR-arrays directly.
John BG
2017-1-13
Well, it's Marc's question, why don't you let Marc decide?
John BG
2017-1-14
To Marc Cousloulis:
did you mark this question as Accepted Answer or did some one else mark it as if you had accepted it?
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