~ means NOT so *isempty* tells you if the vector is empty and *~isempty* tells you if the vector is _not_ empty. Answer from Adam on mathworks.com
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Reddit
reddit.com › r/matlab › why does isempty return false?
r/matlab on Reddit: Why does isempty return false?
September 1, 2015 -

I am fairly new to MatLab and am using it to inspect an array of strings to determine whether each element contains a string (specifically, the letter 'a'). When prompting isempty(strfind(TEST(1), 'a')), where TEST(1) does not contain an 'a', it returns FALSE (i.e. 0).

strfind(TEST(1), 'a') returns {[]}

Any help resolving this issue and possibly helping me understand why the result is not TRUE (i.e. 1)?

Edit: Wow thank-you for all of the thorough responses. I'll get back to working on my project tomorrow at work. This looks to be a very supportive community - although the submitted posts seem to get downvoted a lot.

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MathWorks
mathworks.com › matlabcentral › answers › 378004-why-is-an-empty-string-not-empty-isempty-returns-true-but-isempty-returns-false
Why is an empty string not empty? isempty('') returns true, but isempty("") returns false - MATLAB Answers - MATLAB Central
January 19, 2018 - On one hand, Cobeldick is right that changing isempty("") to return true would produce problems for someone who needs "" to not be empty; on the other hand, there is a huge codebase out there, including mine, which tests for empty strings with isempty(...) and which did not anticipate the introduction into matlab of string objects for which isempty("") would return false.
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Northwestern University
ece.northwestern.edu › local-apps › matlabhelp › techdoc › ref › isempty.html
isempty (MATLAB Functions)
tf = isempty(A) returns logical true (1) if A is an empty array and logical false (0) otherwise. An empty array has at least one dimension of size zero, for example, 0-by-0 or 0-by-5.
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MathWorks
mathworks.com › matlabcentral › answers › 769592-different-outcome-cellfun-isempty-vs-cellfun-isempty
different outcome cellfun(@isempty,..) vs cellfun('isempty',...) - MATLAB Answers - MATLAB Central
November 17, 2020 - https://www.mathworks.com/matlabcentral/answers/769592-different-outcome-cellfun-isempty-vs-cellfun-isempty#answer_645057 ... I recommend you avoid using the 'isempty' syntax in new code. It is present for backwards compatibility with (very) old code and its behavior does differ from the function handle syntax as stated in the description of the func input argument on the documentation page for the cellfun function.
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MathWorks
mathworks.com › matlab › language fundamentals › data types › characters and strings
Test for Empty Strings and Missing Values - MATLAB & Simulink
Create an array of empty strings using the strings function. Each element of the array is a string with no characters. ... Test if str is an empty string by comparing it to an empty string. ... Do not use the isempty function to test for empty strings. A string with zero characters still has a size of 1-by-1.
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Rip Tutorial
riptutorial.com › all and any with empty arrays
MATLAB Language Tutorial => All and Any with empty arrays
That is not the case in MATLAB with empty arrays. ... So if for example you are comparing all elements of an array with a certain threshold, you need to be aware of the case where the array is empty: >> A=1:10; >> all(A>5) ans = 0 >> A=1:0; >> all(A>5) ans = 1 · Use the built-in function isempty ...
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MathWorks
mathworks.com › control system toolbox › dynamic system models › linear system representation › model attributes
isempty - Determine whether dynamic system model is empty - MATLAB
isempty(sys) returns a logical value of 1 (true) if the dynamic system model sys has no input or no output, and a logical value of 0 (false) otherwise. Where sys is a frd model, isempty(sys) returns 1 when the frequency vector is empty.
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Rdrr.io
rdrr.io › github › andrewhooker › PopED › man › isempty.html
isempty: Function written to match MATLAB's isempty function in andrewhooker/PopED: Population (and Individual) Optimal Experimental Design
October 10, 2024 - Other MATLAB: cell(), diag_matlab(), feval(), fileparts(), ones(), rand(), randn(), size(), tic(), toc(), zeros() isempty(zeros(2,3)) isempty(zeros(2,0)) isempty(c(1,2,3))
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MathWorks
mathworks.com › matlabcentral › answers › 2600-isempty
isempty - MATLAB Answers - MATLAB Central
Hello, could anyone point out how to check a empty set? I try isempty, seems wrong a = [1 3 2] a = 1 3 2 K>> b = [1 3 2] b = 1 3 ...
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MathWorks
mathworks.com › matlab › language fundamentals › matrices and arrays
isempty - Determine whether array is empty - MATLAB
TF = isempty(A) returns logical 1 (true) if A is empty, and logical 0 (false) otherwise. An empty array, table, or timetable has at least one dimension with length 0, such as 0-by-0 or 0-by-5. ... Create a 3-D array with one dimension length equal to zero, and determine if it is empty. ... Compare empty arrays to arrays containing missing values. In MATLAB®, an empty array has at least one dimension length equal to zero.