How do I display strings and numbers together in MATLAB? - matlab

I have a 500-by-1 matrix of strings S and a 500-by-1 matrix of numbers N. I want to see them in the variable editor together like this:
S(1) N(1)
S(2) N(2)
...
S(500) N(500)
Is this possible?

The following should allow you to look at the variables together in the Command Window:
disp([char(S) blanks(numel(N))' num2str(N)]);
The array S (which I presume is a cell array) is converted to a character array using the function CHAR. It's then concatenated with a column vector of blanks (made using the function BLANKS) and then a string representation of the numeric array N (made using the function NUM2STR). This is then displayed using the function DISP.

Speaking narrowly to your question, just convert the numbers to cells. You'll have a single variable that the array editor can handle.
X = [ S num2cell(N) ];
More broadly, here's an array-oriented variant of sprintf that's useful for displaying records constructed from parallel arrays. You'd call it like this. I use something like this for displaying tabular data a lot.
sprintf2('%-*s %8g', max(cellfun('prodofsize',S)), S, N)
Here's the function.
function out = sprintf2(fmt, varargin)
%SPRINTF2 Quasi-"vectorized" sprintf
%
% out = sprintf2(fmt, varargin)
%
% Like sprintf, but takes arrays of arguments and returns cellstr. This
% lets you do formatted output on nonscalar arrays.
%
% Example:
% food = {'wine','cheese','fancy bread'};
% price = [10 6.38 8.5];
% sprintf2('%-12s %6.2f', food, price)
% % Fancier formatting with width detection
% sprintf2('%-*s %6.2f', max(cellfun('prodofsize',food)), food, price)
[args,n] = promote(varargin);
out = cell(n,1);
for i = 1:n
argsi = grab(args, i);
out{i} = sprintf(fmt, argsi{:});
end
% Convenience HACK for display to command line
if nargout == 0
disp(char(out));
clear out;
end
function [args,n] = promote(args)
%PROMOTE Munge inputs to get cellstrs
for i = 1:numel(args)
if ischar(args{i})
args{i} = cellstr(args{i});
end
end
n = cellfun('prodofsize', args);
if numel(unique(n(n > 1))) > 1
error('Inconsistent lengths in nonscalar inputs');
end
n = max(n);
function out = grab(args, k)
%GRAB Get the kth element of each arg, popping out cells
for i = 1:numel(args)
if isscalar(args{i})
% "Scalar expansion" case
if iscell(args{i})
out{i} = args{i}{1};
else
out{i} = args{i};
end
else
% General case - kth element of array
if iscell(args{i})
out{i} = args{i}{k};
else
out{i} = args{i}(k);
end
end
end

Related

Function call with variable number of input arguments when number of input arguments is not explicitly known

I have a variable pth which is a cell array of dimension 1xn where n is a user input. Each of the elements in pth is itself a cell array and length(pth{k}) for k=1:n is variable (result of another function). Each element pth{k}{kk} where k=1:n and kk=1:length(pth{k}) is a 1D vector of integers/node numbers of again variable length. So to summarise, I have a variable number of variable-length vectors organised in a avriable number of cell arrays.
I would like to try and find all possible intersections when you take a vector at random from pth{1}, pth{2}, {pth{3}, etc... There are various functions on the File Exchange that seem to do that, for example this one or this one. The problem I have is you need to call the function this way:
mintersect(v1,v2,v3,...)
and I can't write all the inputs in the general case because I don't know explicitly how many there are (this would be n above). Ideally, I would like to do some thing like this;
mintersect(pth{1}{1},pth{2}{1},pth{3}{1},...,pth{n}{1})
mintersect(pth{1}{1},pth{2}{2},pth{3}{1},...,pth{n}{1})
mintersect(pth{1}{1},pth{2}{3},pth{3}{1},...,pth{n}{1})
etc...
mintersect(pth{1}{1},pth{2}{length(pth{2})},pth{3}{1},...,pth{n}{1})
mintersect(pth{1}{1},pth{2}{1},pth{3}{2},...,pth{n}{1})
etc...
keep going through all the possible combinations, but I can't write this in code. This function from the File Exchange looks like a good way to find all possible combinations but again I have the same problem with the function call with the variable number of inputs:
allcomb(1:length(pth{1}),1:length(pth{2}),...,1:length(pth{n}))
Does anybody know how to work around this issue of function calls with variable number of input arguments when you can't physically specify all the input arguments because their number is variable? This applies equally to MATLAB and Octave, hence the two tags. Any other suggestion on how to find all possible combinations/intersections when taking a vector at random from each pth{k} welcome!
EDIT 27/05/20
Thanks to Mad Physicist's answer, I have ended up using the following which works:
disp('Computing intersections for all possible paths...')
grids = cellfun(#(x) 1:numel(x), pth, 'UniformOutput', false);
idx = cell(1, numel(pth));
[idx{:}] = ndgrid(grids{:});
idx = cellfun(#(x) x(:), idx, 'UniformOutput', false);
idx = cat(2, idx{:});
valid_comb = [];
k = 1;
for ii = idx'
indices = reshape(num2cell(ii), size(pth));
selection = cellfun(#(p,k) p{k}, pth, indices, 'UniformOutput', false);
if my_intersect(selection{:})
valid_comb = [valid_comb k];
endif
k = k+1;
end
My own version is similar but uses a for loop instead of the comma-separated list:
disp('Computing intersections for all possible paths...')
grids = cellfun(#(x) 1:numel(x), pth, 'UniformOutput', false);
idx = cell(1, numel(pth));
[idx{:}] = ndgrid(grids{:});
idx = cellfun(#(x) x(:), idx, 'UniformOutput', false);
idx = cat(2, idx{:});
[n_comb,~] = size(idx);
temp = cell(n_pipes,1);
valid_comb = [];
k = 1;
for k = 1:n_comb
for kk = 1:n_pipes
temp{kk} = pth{kk}{idx(k,kk)};
end
if my_intersect(temp{:})
valid_comb = [valid_comb k];
end
end
In both cases, valid_comb has the indices of the valid combinations, which I can then retrieve using something like:
valid_idx = idx(valid_comb(1),:);
for k = 1:n_pipes
pth{k}{valid_idx(k)} % do something with this
end
When I benchmarked the two approaches with some sample data (pth being 4x1 and the 4 elements of pth being 2x1, 9x1, 8x1 and 69x1), I got the following results:
>> benchmark
Elapsed time is 51.9075 seconds.
valid_comb = 7112
Elapsed time is 66.6693 seconds.
valid_comb = 7112
So Mad Physicist's approach was about 15s faster.
I also misunderstood what mintersect did, which isn't what I wanted. I wanted to find a combination where no element present in two or more vectors, so I ended writing my version of mintersect:
function valid_comb = my_intersect(varargin)
% Returns true if a valid combination i.e. no combination of any 2 vectors
% have any elements in common
comb_idx = combnk(1:nargin,2);
[nr,nc] = size(comb_idx);
valid_comb = true;
k = 1;
% Use a while loop so that as soon as an intersection is found, the execution stops
while valid_comb && (k<=nr)
temp = intersect(varargin{comb_idx(k,1)},varargin{comb_idx(k,2)});
valid_comb = isempty(temp) && valid_comb;
k = k+1;
end
end
Couple of helpful points to construct a solution:
This post shows you how to construct a Cartesian product between arbitrary arrays using ndgrid.
cellfun accepts multiple cell arrays simultaneously, which you can use to index specific elements.
You can capture a variable number of arguments from a function using cell arrays, as shown here.
So let's get the inputs to ndgrid from your outermost array:
grids = cellfun(#(x) 1:numel(x), pth, 'UniformOutput', false);
Now you can create an index that contains the product of the grids:
index = cell(1, numel(pth));
[index{:}] = ndgrid(grids{:});
You want to make all the grids into column vectors and concatenate them sideways. The rows of that matrix will represent the Cartesian indices to select the elements of pth at each iteration:
index = cellfun(#(x) x(:), index, 'UniformOutput', false);
index = cat(2, index{:});
If you turn a row of index into a cell array, you can run it in lockstep over pth to select the correct elements and call mintersect on the result.
for i = index'
indices = num2cell(i');
selection = cellfun(#(p, i) p{i}, pth, indices, 'UniformOutput', false);
mintersect(selection{:});
end
This is written under the assumption that pth is a row array. If that is not the case, you can change the first line of the loop to indices = reshape(num2cell(i), size(pth)); for the general case, and simply indices = num2cell(i); for the column case. The key is that the cell from of indices must be the same shape as pth to iterate over it in lockstep. It is already generated to have the same number of elements.
I believe this does the trick. Calls mintersect on all possible combinations of vectors in pth{k}{kk} for k=1:n and kk=1:length(pth{k}).
Using eval and messing around with sprintf/compose a bit. Note that typically the use of eval is very much discouraged. Can add more comments if this is what you need.
% generate some data
n = 5;
pth = cell(1,n);
for k = 1:n
pth{k} = cell(1,randi([1 10]));
for kk = 1:numel(pth{k})
pth{k}{kk} = randi([1 100], randi([1 10]), 1);
end
end
% get all combs
str_to_eval = compose('1:length(pth{%i})', 1:numel(pth));
str_to_eval = strjoin(str_to_eval,',');
str_to_eval = sprintf('allcomb(%s)',str_to_eval);
% use eval to get all combinations for a given pth
all_combs = eval(str_to_eval);
% and make strings to eval in intersect
comp = num2cell(1:numel(pth));
comp = [comp ;repmat({'%i'}, 1, numel(pth))];
str_pattern = sprintf('pth{%i}{%s},', comp{:});
str_pattern = str_pattern(1:end-1); % get rid of last ,
strings_to_eval = cell(length(all_combs),1);
for k = 1:size(all_combs,1)
strings_to_eval{k} = sprintf(str_pattern, all_combs(k,:));
end
% and run eval on all those strings
result = cell(length(all_combs),1);
for k = 1:size(all_combs,1)
result{k} = eval(['mintersect(' strings_to_eval{k} ')']);
%fprintf(['mintersect(' strings_to_eval{k} ')\n']); % for debugging
end
For a randomly generated pth, the code produces the following strings to evaluate (where some pth{k} have only one cell for illustration):
mintersect(pth{1}{1},pth{2}{1},pth{3}{1},pth{4}{1},pth{5}{1})
mintersect(pth{1}{1},pth{2}{1},pth{3}{1},pth{4}{2},pth{5}{1})
mintersect(pth{1}{1},pth{2}{1},pth{3}{1},pth{4}{3},pth{5}{1})
mintersect(pth{1}{1},pth{2}{1},pth{3}{2},pth{4}{1},pth{5}{1})
mintersect(pth{1}{1},pth{2}{1},pth{3}{2},pth{4}{2},pth{5}{1})
mintersect(pth{1}{1},pth{2}{1},pth{3}{2},pth{4}{3},pth{5}{1})
mintersect(pth{1}{2},pth{2}{1},pth{3}{1},pth{4}{1},pth{5}{1})
mintersect(pth{1}{2},pth{2}{1},pth{3}{1},pth{4}{2},pth{5}{1})
mintersect(pth{1}{2},pth{2}{1},pth{3}{1},pth{4}{3},pth{5}{1})
mintersect(pth{1}{2},pth{2}{1},pth{3}{2},pth{4}{1},pth{5}{1})
mintersect(pth{1}{2},pth{2}{1},pth{3}{2},pth{4}{2},pth{5}{1})
mintersect(pth{1}{2},pth{2}{1},pth{3}{2},pth{4}{3},pth{5}{1})
mintersect(pth{1}{3},pth{2}{1},pth{3}{1},pth{4}{1},pth{5}{1})
mintersect(pth{1}{3},pth{2}{1},pth{3}{1},pth{4}{2},pth{5}{1})
mintersect(pth{1}{3},pth{2}{1},pth{3}{1},pth{4}{3},pth{5}{1})
mintersect(pth{1}{3},pth{2}{1},pth{3}{2},pth{4}{1},pth{5}{1})
mintersect(pth{1}{3},pth{2}{1},pth{3}{2},pth{4}{2},pth{5}{1})
mintersect(pth{1}{3},pth{2}{1},pth{3}{2},pth{4}{3},pth{5}{1})
mintersect(pth{1}{4},pth{2}{1},pth{3}{1},pth{4}{1},pth{5}{1})
mintersect(pth{1}{4},pth{2}{1},pth{3}{1},pth{4}{2},pth{5}{1})
mintersect(pth{1}{4},pth{2}{1},pth{3}{1},pth{4}{3},pth{5}{1})
mintersect(pth{1}{4},pth{2}{1},pth{3}{2},pth{4}{1},pth{5}{1})
mintersect(pth{1}{4},pth{2}{1},pth{3}{2},pth{4}{2},pth{5}{1})
mintersect(pth{1}{4},pth{2}{1},pth{3}{2},pth{4}{3},pth{5}{1})
As Madphysicist pointed out, I misunderstood the initial structure of your initial cell array, however the point stands. The way to pass an unknown number of arguments to a function is via comma-separated-list generation, and your function needs to support it by being declared with varargin. Updated example below.
Create a helper function to collect a random subcell from each main cell:
% in getRandomVectors.m
function Out = getRandomVectors(C) % C: a double-jagged array, as described
N = length(C);
Out = cell(1, N);
for i = 1 : length(C)
Out{i} = C{i}{randi( length(C{i}) )};
end
end
Then assuming you already have an mintersect function defined something like this:
% in mintersect.m
function Intersections = mintersect( varargin )
Vectors = varargin;
N = length( Vectors );
for i = 1 : N; for j = 1 : N
Intersections{i,j} = intersect( Vectors{i}, Vectors{j} );
end; end
end
Then call this like so:
C = { { 1:5, 2:4, 3:7 }, {1:8}, {2:4, 3:9, 2:8} }; % example double-jagged array
In = getRandomVectors(C); % In is a cell array of randomly selected vectors
Out = mintersect( In{:} ); % Note the csl-generator syntax
PS. I note that your definition of mintersect differs from those linked. It may just be you didn't describe what you want too well, in which case my mintersect function is not what you want. What mine does is produce all possible intersections for the vectors provided. The one you linked to produces a single intersection which is common to all vectors provided. Use whichever suits you best. The underlying rationale for using it is the same though.
PS. It is also not entirely clear from your description whether what you're after is a random vector k for each n, or the entire space of possible vectors over all n and k. The above solution does the former. If you want the latter, see MadPhysicist's solution on how to create a cartesian product of all possible indices instead.

Converting a cell to matrix in the presence of a for loop

I am running a LASSO estimation method alongside a for loop.
Here is the code:
%Lasso
data = rand(246,3); %random data for illistrative purposes
XL1 = lagmatrix(data,1); %Lags the data matrix by one period
ydata = data; %Specifies the dependent variable
ydata([1],:)=[]; %Removes the top row due to the lagged X
XL1([1],:)=[]; %Removes the top row of the lagged X with become a NaN from lagmatrix
for ii = 1:3 %For loop to complete LASSO for all industries
y = ydata(:,ii); %y is the industry we are trying to forecast
rng default % For reproducibility, as the LASSO uses some random numbers
[B,FitInfo] = lasso([XL1],y,'CV',10,'PredictorNames',{'x1','x2','x3'});
idxLambdaMinMSE = FitInfo.IndexMinMSE;
ii
minMSEModelPredictors = FitInfo.PredictorNames(B(:,idxLambdaMinMSE)~=0)
end
The output that the LASSO provides is
ii = 1
minMSEModelPredictors =
1×1 cell array
{'x2'}
ii = 2
minMSEModelPredictors =
1×5 cell array
{'x1'} {'x2'} {'x3'}
ii = 3
minMSEModelPredictors =
1×2 cell array
{'x2'} {'x3'}
For the purposes of automating this, I need the result to be reported in the following manner,
Results = {[2],[1 2 3],[2 3]};
I know this is a long shot, but it would be helpful as the above is easy to type out but If I increase the dimensions, this becomes a very difficult task.
Each output of minMSEModelPredictors is a cell array of the form
minMSEModelPredictors = {'x1', 'x2', 'x3'};
We can use strrep to get rid of the 'x' (or just don't have an 'x' in your predictor names to begin with), and str2double to convert the cell array to a numeric array.
Then storing the results is trivial...
Result = cell(1,3); % Initialise output
for ii = 1:3
% stuff...
minMSEModelPredictors = FitInfo.PredictorNames(B(:,idxLambdaMinMSE)~=0);
Result{ii} = str2double( strrep( minMSEModelPredictors, 'x', '' ) );
end

Input parser: one parameter dependent from another parameter

I am using the input parser functionality a lot but now I am facing the following issue:
I am coding an object that computes the rate-of-change of time series, i.e. one input argument is a matrix of doubles (timeSeries). A second input parameter is the time period used to compute the rate-of-change (lag). lag can be a vector wherby different rate-of-changes will be computed. A third input vector is called weightVector. weightVector will be used to compute an average of all rate-of-changes and applies the appropriate weights to the respective rate-of-change results.
Now, I always like to define some default values when using input parser. I would like to define weightVector to be an equal weighted vector. However, the length of the default weightVector is dependent on the length of lag. For example, if lag = [1,2,3], then weightVectorshould equal [1/3, 1/3, 1/3]. How am I supposed to code a situation like this? My current code for the constructor looks like this:
function obj = roc(timeSeries, varargin)
%% Input parser
% 1. Create input parser instance
p = inputParser;
% 2. Default values for input arguments
default_lag = 1;
default_weightVector = 1/length(lag); % This line is causing
% problems as LAG isn't
% defined, yet.
% 3. Validation of input arguments
valid_lag = {'vector', 'nonempty', 'integer', 'positive'};
check_lag = #(x) validateattributes(x, {'numeric'}, valid_lag);
valid_weightVector = {'vector', 'nonempty'};
check_weightVector = #(x) validateattributes(x, {'numeric'}, ...
valid_weightVector);
% 4. Add input arguments to input scheme
p.addRequired('timeSeries');
p.addParamater('lag', default_lag, check_lag);
p.addParameter('weightVector', default_weightVector, check_weightVector);
% 5. Parse input arguments
parse(p, timeSeries, varargin{:});
% 6. Assign results to variables
lag = p.Results.lag;
weightVector = p.Results.weightVector;
%% Main code
end % Constructor
function obj = roc(timeSeries, varargin)
%% Input parser
% 1. Create input parser instance
p = inputParser;
% 2. Default values for input arguments
default_lag = 1;
default_weightVector = 1;
% 3. Validation of input arguments
valid_lag = {'vector', 'nonempty', 'integer', 'positive'};
check_lag = #(x) validateattributes(x, {'numeric'}, valid_lag);
% 4. Add input arguments to input scheme
p.addRequired('timeSeries');
p.addParameter('lag', default_lag, check_lag);
p.addParameter('weightVector', default_weightVector);
% 5. Parse input arguments
parse(p, timeSeries, varargin{:});
% 6. Assign results to variables
lag = p.Results.lag;
if check_weightVector(p.Results.weightVector, lag) == true
weightVector = p.Results.weightVector;
end
function vout = check_weightVector(weightVector, lag) % validation function
if length(lag) ~= length(weightVector)
error('lengthWeightVector:WrongNumberOfElements', 'The number of elements in "weightVector" must correspond to the number of elements in "lag"');
elseif sum(weightVector) ~= 1
error('sumWeightVector:SumNotEqualToOne', 'The sum of elements in "weightVector" must equal 1');
end
vout = true;
end
%% Main code
end

Using varargin inputs as structure name and string

Is there a way to use varargin inputs in several different forms. I would like the varargin inputs to become the name of a structure, but I also want it be passed into a fprintf which doesn't accept cell or structure arrays. If I have a function like:
function[] = myfunc(varargin)
for k = varargin
for m = 'ABC'
for n = 1:10
varname = sprintf('%c%d',m,n);
filename = sprintf('Images\\%s',varname);
fprintf('Take measurement %s for %s\n',k,varname);
image = imread(fullfile(filename));
pause
cursor_info = evalin('base','cursor_info');
p1 = cursor_info(2).Position
p2 = cursor_info(1).Position
[d,s] = measure(p1,p2) %measure is a separate function in my directory
k.(varname) = [d,s]
end
end
save('Distances,'k','-append')
end
My function is used to analyze several pictures, hence the ABC and 1:10 for loops. If I call the function with inputs of 'M1', 'M2', 'M3', I would like the function to create structures M1, M2, and M3 with A1,B1,C1 - A10,B10,C10 as the field names. [d,s] will be the data saved in each field which is found with the imagesc GUI and function measure.
The problem is that in the loop iterations I want the varargin inputs to be inputed into fprintf and I also want the varargin inputs to become the structure name. I can edit the code so that fprintf accepts the inputs using the function char. But is it possible to have an input in a function become the name of structure to fill with data? And if so, the solution still has to allow the iterator k to be passed into fprintf.
You can have a single structure that holds all k-s, then you can save it with '-struct' option to "strip" it into its fields:
function[] = myfunc(varargin)
for k = varargin
for m = 'ABC'
for n = 1:10
% your stuff here... I am too lazy to copy it...
[d,s] = measure(p1,p2) %measure is a separate function in my directory
meta.(k{1}).(varname) = [d,s] ; % note the {1} for k, loop over cell elements
end
end
save('Distances','meta','-struct','-append'); % not 100% sure -append wirks with -struct, you'll have to verify that...
end

matlab - is there a function which echo text of file ?

Since it is not possible to have a script and a function definition in the same file , I thought to echo the function which I want to attach in the script such that I get a script with function code and then some usage with this function .
For example -
func1.m
function [result] = func1(x)
result=sqrt(x) ;
end
script1.m
echo(func1.m) ;
display(func1(9))
Desire output for script1.m
function [result] = func1(x)
result=sqrt(x) ;
end
display(func1(9))
3
Have you any idea for that ?
Since a convoluted solution was already proposed, why not stating the obvious?
Matlab has a built-in command that does exactly what you want. It is called type:
>> type('mean')
will give you this:
function y = mean(x,dim)
%MEAN Average or mean value.
% For vectors, MEAN(X) is the mean value of the elements in X. For
% matrices, MEAN(X) is a row vector containing the mean value of
% each column. For N-D arrays, MEAN(X) is the mean value of the
% elements along the first non-singleton dimension of X.
%
% MEAN(X,DIM) takes the mean along the dimension DIM of X.
%
% Example: If X = [0 1 2
% 3 4 5]
%
% then mean(X,1) is [1.5 2.5 3.5] and mean(X,2) is [1
% 4]
%
% Class support for input X:
% float: double, single
%
% See also MEDIAN, STD, MIN, MAX, VAR, COV, MODE.
% Copyright 1984-2005 The MathWorks, Inc.
% $Revision: 5.17.4.3 $ $Date: 2005/05/31 16:30:46 $
if nargin==1,
% Determine which dimension SUM will use
dim = min(find(size(x)~=1));
if isempty(dim), dim = 1; end
y = sum(x)/size(x,dim);
else
y = sum(x,dim)/size(x,dim);
end
You could use this:
function echo(mfile)
filename=which(mfile);
if isempty(filename)
fprintf('Invalid input - check you are inputting a string.');
return;
end
fid=fopen(filename,'r');
if (fid<0)
fprintf('Couldn''t open file.');
end
file=fread(fid,Inf);
fclose(fid);
fprintf('%s',file);
end
This will open a file, read it, and print it. Note that you need to provide the input as a string, i.e. with single quotes around it, and need to have '.m' at the end:
echo('fread.m')
Not
echo(fread.m) % This won't work
echo('fread') % This won't work
Just for completeness, there's also dbtype which prepends line numbers.