MATLAB: Numeric values need to be equalize to symbolic values.

doublesymbolic

distances=[100 120;200 220]
  points_id=[{'p1'} {'p2'};{'p3'} {'p4'}]

% I need to equalize each matrixes to each other.

%for example, 100='p1' , 120='p2' , 200='p3' , 220='p4'

%then, when I need to learn the numeric values symbol, for example, 220, I could be retrive 'p4' as a symbolic assigned value of 220.

Best Answer

Here are two functions, the first will find point_id given an element of the distances matrix:

pointfind = @(d) points_id(find(distances == d));

p = pointfind(220)

returns

p = 
      'p4'

and the second one will find the corresponding element in distances given an element in the point_id array:

distfind = @(p) distances(find(cellfun(@isempty, strfind(points_id, p)) == 0));

d = distfind('p4')

returns

d =
     220

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MATLAB: Find function with floating points number

This revision of pointfind should work:

pointfind = @(d) points_id(find(fix(distances*10^(length(num2str(rem(d,1)))-2))/(10^(length(num2str(rem(d,1)))-2)) == d));

(It obviously all goes on one line, although it wraps here.)

You are dealing with differences in precision between the values stored in distances and the precision in the argument ‘d’ you present to pointfind. The revised version of pointfind truncates the elements of distances to the precision of ‘d’ before it does the comparison. It works with decimal fractions now.

MATLAB: How to access a structure array using a loop

First, note that with your example, at the end p is a structure with just one field 'p10'. To create the structure you want:

p = struct('p1', {p1}, 'p2', {p2}, 'p3', {p3}, ...)

Also note that you don't need to put the field contents into a cell array, unless this content is itself a cell array. so:

 p = struct('p1', p1, 'p2', p2, ...)

may work just as well.

Secondly, your for loop is not going to work, ['p1' 'p2' 'p3' ...] is exactly the same as 'p1p2p3....', and i will take in turn the values 'p', then '1', then 'p' again, then '2', etc. You need to use a cell array

Finally, to use dynamic field names, you enclose the variable holding the field name in round brackets ().

So:

p = struct('p1',{p1}, 'p2',{p2}, 'p3',{p3}, 'p4',{p4}), 'p5',{p5}, 'p6',{p6}, 'p7',{p7}, 
'p8',{p8}, 'p9',{p9}, 'p10',{p10});
for fn = {'p1', 'p2', 'p3', 'p4', 'p5', 'p6', 'p7', 'p8', 'p9', 'p10'}
%or better: for fn = fieldnames(p)'
   o = p.(fn{1});
end

Best Answer

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