I am trying to compare two cell arrays, 1x160 (a) and 80x1(b). My cell arrays consist of cells which have a number of strings inside. I wanna compare each string ans see if they are equal, then if they are equal, insert to new array, or insert 0 otherwise. I can't find any function for that. I tried 'isequal','strfind' and others. All of them give me next error message:
If any of the input arguments are cell arrays, the first must be a
cell array of strings and the second must be a character array.
Here is my code!
function [inter]=Intersect2(a,b)
int=cell(0);
b2=[b;b];
for i=1:length(a)
if a{i,1}==b2{i,1}(1) ( or 'isequal','strfind')
int{i}=a{i};
else
int{i}=0;
end
end
There are many ways to compare character arrays, one of which is strcmp.
We'll use cellfun as well to avoid looping.
a = {'Dude', 'I', 'am', 'a', 'moose'};
b = {'Well', 'I', 'am', 'a', 'mouse'};
index = cellfun(#strcmp, a, b);
This will compare each element of a against the corresponding element in b, returning a logical array index that is 1 when the elements match and 0 when they do not.
Use this to assign matching values:
int = cell(1, length(a));
int(index) = a(index);
int =
[] 'I' 'am' 'a' []
You can extend this concept to find the set intersection if you wish.
Related
I have a cell array that contains a lot of NaN. But for whatever reason the isnan function can't detect them (hence this doesn't work cellfun(#(Iarray) any(isnan(Iarray)),Iarray);) so I figured it was actually strings that contains NaN.
I perform two things on this array : cleaning empty rows and columns and removing NaN (well trying to).
So I want to replace all the NaN by empty cells and then perform to clean all empty cells with the isempty function. I'll use a loop and if char(x(i,j))=='NaN'.
So here comes my problem I want to empty a cell and then detect that cell with the isempty function but I have no idea how. I have tried x(1,2)= [], x(1,2)= {[]}, x(1,2)='' but none of those gives a 1 for isempty(x(1,2)) for example.
Does anyone know how to solve my problem?
Thanks in advance!
If you want to empty the content of a cell you can use :
x{1,2} = [];
There is a difference between indexing using parentheses () and brackets {}. You can think a cell array as an array of cells that each cell contains a value such as 1 ,2 , []. When a cell is indexed with parentheses it returns the result as cell (or more precisely as an array of type cell) but when it is indexed with brackets it returns the content of the cell (or more precisely as a comma separated list containing the contents of the indexed cells). So when you write such an expression:
x(1,2) = [];
It removes the second element from the array of cells and behaves like indexing other array types. For example when you want to remove the second element of a = [1 2 3] you can use a(2)=[].
But when you write x{1,2} = []; it accesses the content of the cell and sets it to a null array [0 x 0] of type double that is empty.
Likewise a={} is a [0 x 0] null array of cells and b={[]} is an [1 x 1] array of cells that its first element contains a null array [0 x 0] of type double. When you use isempty(b) it returns false because it contains an element and when you use isempty(b(1)) it returns false because b(1) returns an array of cells that contains an element but when you use isempty(b{1}) it returns true because the {} operator extracts the contents of the first cell that is a null array.
In short, cells can be accessed using both () and {}, and based on the situation [] has different functionalities: a) removing element b) null array.
Assume I have A that is a 64x1 cell array.
Each of the 64 cells contains another cell with a string (which is a number, i.e. 11)
A{1, 1}{1, 1} = ’11’ (char)
A{2, 1}{1, 1} = ’13’ (char)
How can I create a numeric array such as
A = [11,13,…]
The cell2mat function seems to work only on “first level” cell array:
cell2mat does not support cell arrays containing cell arrays or objects.
You can use cellfun to convert the contents of each individual cell in A to doubles.
A{1, 1}{1, 1} = '11';
A{2, 1}{1, 1} = '13';
A_array = cellfun(#(a) str2double(a), A)
Breakdown of the function: #(a) passes the contents of each cell of A to the variable a, which can be converted to doubles using str2double(a).
It's quite simple, however you need split it to two steps. Let's assume we have simple 1x4 string array:
A= {'11','13','15','17'};
To convert it you need store the content in temporary variable S, then use sscanf to generate final result:
S = sprintf('%s ', A{:});
Result = sscanf(S, '%f')
The only problem is that it will be column vector. If you need it in a row, you can just transpose(Results).
I'm not sure I entirely understand your question. If I've got it right, you're talking about a cell array like asd below
asd=cell(61,1);
for ii=1:64
asd{ii}={['test',num2str(ii)]}
end
If I understand your goal correctly, I think the following does it somewhat neatly
A=char([asd{:}])
Then if you want to convert the strings to numbers (which wouldn't work for my test, but might for your strings), just use str2num on this new vector
Transform A into a comma-separated list of cells, then horizontally concatenate these cells and finally apply str2double;
A = str2double([A{:}]);
I'm writing some code to split up a 180x2 matlab cell array based on a string in the second column. This string is one of EP,GA,PS,SS or SA. In python I could define empty lists then use conditionals to iterate over the elements of the list and append them to the relevant lists.
The Code
EP=[];
GA=[];
PS=[];
SA=[];
SS=[];
for i=1:size(d),
if strcmp(d(i,2),'EP'),
append(EP,d(i,1))
elseif strcmp(d(i,2),'GA'),
append(GA,i)
elseif strcmp(d(i,2),'PS'),
append(PS,i)
elseif strcmp(d(i,2),'SA'),
append(SA,i)
elseif strcmp(d(i,2),'SS'),
append(SS,i)
end
end
Note that 'd' is a 180x2 cell array that I copied and pasted into matlab rather than import. The general structure of the data however is:
12.9089000000000 'EP'
13.3697000000000 'SA'
13.4335000000000 'EP'
13.5302000000000 'PS'
13.8434000000000 'EP'
14.2583000000000 'EP'
14.8221000000000 'GA'
However when attempting this tactic in matlab I get an error:
Error using append (line 38)
Wrong number of input arguments for obsolete
matrix-based syntax.
Error in Boxplot_All_results (line 12)
append(GA,i)
Could somebody tell me the correct way of doing this in matlab
First of all, please not that d is a cell array. To index the elements of a cell array, use {}. If you index using () like you did, you end up with a small cell array containing only the indexed element(s).
To append in Matlab you basically have two choices:
%concatenate the list with a scalar. Also suitable for two lists.
EP=[EP,d{i,1}] %could also be done using cat
%append to the end
EP(end+1)=d{i,1}
While this fixes the problem, I recommend to implement it on a more generic way:
names={'EP','GA','PS','SA','SS'}
s=struct()
for idx=1:numel(names)
s.(names{idx})=[d{strcmpi(d(:,2),names{idx}),1}]
end
You end up with a struct containing the data you want.
Can you show MatLab code?
How do you append those values to cell array?
You can just create one a = {}
and then append element at the size+1 index. That operation extends your cell array.
Or you can also do a trick like that: a = [a; {value}]
To append elements to a cell array, a correct syntax would be:
for i=1:size(d),
if strcmp(d(i,2),'EP'),
EP = [EP ; d(i,1) ] ; %// append(EP,d(i,1))
elseif strcmp(d(i,2),'GA'),
GA = [GA ; d(i,1) ] ; %// append(GA,i)
but there are more ways, as you can read in the documentation: Add Cells to a Cell Array
There are also more ways to build your final extracted arrays in one assignment instead of having them growing dynamically (mLint will complain about that by the way).
Get the indices of the elements which satisfy your condition then create an array with only the matching elements. For example:
iEP = cellfun( #(c) strcmp(c,'EP') , d(:,2) ) ; %// logical array of indexes where the condition is true
EP = d(iEP,1) ; %// Create "EP" in one assignment - EP is a [cell] array
If you only have numeric values to retrieve in these new variables, may be having a double array instead of a cell array will be convenient :
iGA = cellfun( #(c) strcmp(c,'GA') , d(:,2) ) ; %// logical array of indexes where the condition is true
GA = cell2mat( d(iGA,1) ) ; %// Create "GA" in one assignment - GA is a [double] array
Of course you can bypass the intermediate variable holding the indices:
PS = d( cellfun(#(c)strcmp(c,'PS'),d(:,2)),1) ; %// Create "PS" in one assignment [cell] array
SA = cell2mat(d(cellfun(#(c)strcmp(c,'SA'),d(:,2)),1)) ; %// Create "SA" in one assignment [double] array
I have a cell array (2000*10) with each cell containing a string such as '25:20:55'.
I want to write a function that accepts 10 inputs (say '25:02:33', '58:69:88', '25:54:96', '48:58:36', '58:54:88' and so on) and looks for a match in each column corresponding to input value for that particular column (i.e. the first input data corresponds to 1st column, 2nd to 2nd column of the stored data and so on.
How can I write a function for the above comparison?
Assuming the cell array contains strings, you can find matches using strcmp:
input = {'25:02:33', '58:69:88', '25:54:96', '48:58:36', '58:54:88'};
match_idx = strcmp(repmat(input, size(cell_data,1),1), cell_data);
If you only want to know if there are matches in the respective columns at all and do not care about the line index of the match, you can do
match = any(match_idx,1);
Use ismember
ismember(your_var, your_cell);
e.g.
c = {'a', 'b', 'c', 'd'};
ismember('b', c)
ans =
1
ismember('q', c)
ans =
0
In your case, something like could work
function arr = myfun(inputvec, inputmat)
for i=1:length(inputvec) %// where inputvec is the cell-vector with the strings you want to search for
arr(i) = ismember(inputvec{i}, inputmat{:,i});
end
My question is easily summarized as: "Why does the following not work?"
teststruct = struct('a',3,'b',5,'c',9)
fields = fieldnames(teststruct)
for i=1:numel(fields)
fields(i)
teststruct.(fields(i))
end
output:
ans = 'a'
??? Argument to dynamic structure reference must evaluate to a valid field name.
Especially since teststruct.('a') does work. And fields(i) prints out ans = 'a'.
I can't get my head around it.
You have to use curly braces ({}) to access fields, since the fieldnames function returns a cell array of strings:
for i = 1:numel(fields)
teststruct.(fields{i})
end
Using parentheses to access data in your cell array will just return another cell array, which is displayed differently from a character array:
>> fields(1) % Get the first cell of the cell array
ans =
'a' % This is how the 1-element cell array is displayed
>> fields{1} % Get the contents of the first cell of the cell array
ans =
a % This is how the single character is displayed
Since fields or fns are cell arrays, you have to index with curly brackets {} in order to access the contents of the cell, i.e. the string.
Note that instead of looping over a number, you can also loop over fields directly, making use of a neat Matlab features that lets you loop through any array. The iteration variable takes on the value of each column of the array.
teststruct = struct('a',3,'b',5,'c',9)
fields = fieldnames(teststruct)
for fn=fields'
fn
%# since fn is a 1-by-1 cell array, you still need to index into it, unfortunately
teststruct.(fn{1})
end
Your fns is a cellstr array. You need to index in to it with {} instead of () to get the single string out as char.
fns{i}
teststruct.(fns{i})
Indexing in to it with () returns a 1-long cellstr array, which isn't the same format as the char array that the ".(name)" dynamic field reference wants. The formatting, especially in the display output, can be confusing. To see the difference, try this.
name_as_char = 'a'
name_as_cellstr = {'a'}
You can use the for each toolbox from http://www.mathworks.com/matlabcentral/fileexchange/48729-for-each.
>> signal
signal =
sin: {{1x1x25 cell} {1x1x25 cell}}
cos: {{1x1x25 cell} {1x1x25 cell}}
>> each(fieldnames(signal))
ans =
CellIterator with properties:
NumberOfIterations: 2.0000e+000
Usage:
for bridge = each(fieldnames(signal))
signal.(bridge) = rand(10);
end
I like it very much. Credit of course go to Jeremy Hughes who developed the toolbox.