Matlab make new array of values without a loop

Question

In Matlab, I don't know the best way to explain this except for an example. Let's say I have an array called tStart and a tDuration length:

tStart = [3,8,15,20,25];
tDuration = 2;

Is there some way to get a new array such that it would be:

[3,4,5,8,9,10,15,16,17,20,21,22,25,26,27]

So what I want is to use the initial tStart array then make up a new array with the starting value and then next corresponding values for the length of tDuration.

If I do [tStart(1:end)+tDuration] I get an array of ending values, but how can I get the start, end, and all the values in between?

If I [tStart(1:end):tStart(1:end)+tDuration] I get an error.

Any help of a way to do this without a loop would be greatly appreciated.

beaker · Accepted Answer · 2020-03-09 20:18:50Z

5

I would use MATLAB's implicit expansion, reshape, and the ordering of 2d arrays.

First, create a 2d array containing the desired values from tStart:

tStart = [3,8,15,20,25];
tDuration = 2;

tDurAdd = [0:tDuration].';  % numbers to add to tStart
tArray = tStart + tDurAdd;

This gives us

tArray =

    3    8   15   20   25
    4    9   16   21   26
    5   10   17   22   27

These are the correct values, now we just have to reshape them to a row vector:

tResult = reshape(tArray, 1, []);

The final array is:

tResult =

    3    4    5    8    9   10   15   16   17   20   21   22   25   26   27

Of course, this can all be done on one line:

tResult = reshape(tStart + [0:tDuration].', 1, []);

answered Mar 9, 2020 at 20:18

beaker

16.9k3 gold badges36 silver badges53 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

laxer Over a year ago

Thank you for your quick answer. Let me know if this should be another question, but when using this method in Scilab it gives an error of Inconsistent row/column dimensions. when trying to make tArray. Should it be the same for Scilab or will that be different? I know that reshape will need to be matrix.

beaker Over a year ago

@laxer I'm not that familiar with Scilab, but I gather from your error that it doesn't support implicit expansion. It also appears that it does not support the alternative in MATLAB, bsxfun. Sorry, but there's not much I can do for you.

laxer Over a year ago

It worked great in MatLab and that is what I specifically asked for, so thank you for your response. It was a lot of help!

Collectives™ on Stack Overflow

Matlab make new array of values without a loop

1 Answer 1

3 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

3 Comments

Your Answer

Sign up or log in

Post as a guest

Related