How to process multiple matrices. Checking whether the elements of a matrix are within the specified range

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Yesbol 2017-2-24

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评论： Yesbol 2017-2-25

Hello. I have 55 matrices 288x1 named Load1, Load2, Load3, ..., Load55. I need to create a for loop which checks whether the values are between 207 and 253. If one of the values exceeds 253 or is less than 207, I need to display the name of this variable. For example, one of the elements of matrix Load7 is 205. In this case, the program should display 'Load7'. Ultimately, I need to get a list of variables which values are not within specified range. Also, the script has to calculate the total number of variables which values are not within the range.

The output of the script shall look like, for example:

The Loads which are not within the range: Load7, Load25, Load37. The total number of loads: 3

Any help is greatly appreciated. Thank you.

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John BG 2017-2-25

may be Yesbol is new in MATLAB and doesn't know how to LOAD THE DATA INTO 2D ARRAY

may be Yesbol knows a way, but would like the experts to show whether there's a better way.

as trivial as it is, would you please supply a valid answer? if you don't I will

regards

John BG <mailto:jgb2012@sky.com jgb2012@sky.com>

Stephen23 2017-2-25

编辑：Stephen23 2017-2-25

Do NOT create lots of variables named Load1, Load2, load3, etc. This will make your code slow and buggy. Read this to know why, and what the much better alternatives are (hint: indexing):

https://www.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval

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Answer 1

dpb 2017-2-24

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编辑：dpb 2017-2-25

在 MATLAB Online 中打开

Given you heed the advice in the comment so the data are in array loads

lo=207; hi=253;                  % set the limits desired
ix=iswithin(loads,lo,hi);        % check all are ok, ix is logical array of locations
isOK=all(ix);                    % if T, all are ok for each column
if all(isOK)
  fprintf('All is well\n')
else
  bad=sum(~isOK);                % number failed columns (loads)
  fmt=['Load %2d' repmat(', %2d',1,bad-1) '\n']  % format string to print offending load(s)
  fprintf(fmt,find(~isOK))       % and print the message
  fprintf('Total number of loads failed: %d\n',bad)  % and the total
end

CAUTION: Air code, untested, but should be close.

iswithin is a utility function of mine--

>> type iswithin
function flg=iswithin(x,lo,hi)
% returns T for values within range of input
% SYNTAX:
%  [log] = iswithin(x,lo,hi)
%      returns T for x between lo and hi values, inclusive
    flg= (x>=lo) & (x<=hi);
  >>

ADDENDUM

Dawned on me not that hard to build some data to test...

>> loads=round(randn(20,3)*12+230)
oads =
 234   237   224
 208   229   226
 242   238   217
 259   233   224
 242   236   228
 226   212   231
 235   218   229
 218   225   237
 253   231   231
 241   244   252
 239   227   234
 219   245   252
 234   236   221
 223   244   236
 226   232   227
 223   222   237
 218   212   237
 219   232   204
 227   240   214
 210   226   213
>> ix=iswithin(loads,lo,hi);
>> isOK=all(ix)
isOK =
   0     1     0
>> bad=sum(~isOK);
>> fmt=['Load %2d' repmat(', %2d',1,bad-1) '\n'];
>> fprintf(fmt,find(isOK==false))
Load  1,  3
>> fprintf('Total number of loads failed: %d\n',bad)
Total number of loads failed: 2
>>

Looks OK to me...

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dpb 2017-2-25

编辑：dpb 2017-2-25

在 MATLAB Online 中打开

I said it was air code! :)

It's complaining that I put the string to dup last instead of first in the argument list.

That syntax error aside, bad is the sum of failures for each column; figured that would be of interest when started but then noticed you were only reporting the total number of columns failed and didn't change variables but didn't update bad, either...

The quick fix is

bad=sum(~isOK);

instead; isOK is the check for columns. This overwrites the total number in each column if you do later want that additional detail, create another variable for it.

Also note it's the isOK array to print as well instead and the find argument is modified to search the whole array; otherwise as wrote initially the indices are only for those failed columns instead of the locations in the larger array.

I'll edit the Answer as well...but still since you didn't provide any data and I didn't want to take time to try to generate some phantom data, it is untested so debugging is partly your job... :)

Yesbol 2017-2-25

THank you!

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Answer 2

John D'Errico 2017-2-24

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And this is only one of the reasons why what you did is a terribly bad idea. Combine all into one matrix. Do it once. Get it over with. And next time, learn not to create multiple numbered arrays.

Instead, learn to create matrices. With a matrix, your question becomes one simple line of code to test them all at once.