MATLAB Central Newsreader - Help appending entered values to an array

Help appending entered values to an array

jeremy — Wed, 23 Jul 2008 02:18:01 -0400

I am a rather new user to the MATLAB world and I am having
some difficulty figuring this out.

I have a mat-file that contains an array of 2 cols and 14
rows. When this mat-file is loaded, it produces a variable
called "hc_actual" which is a 14x2 double.

Here's what I want to do...

Add code to my M-file that will allow me to enter a new X,Y
pair at the command window prompt, append that pair to the
first empty row in the "hc_actual" array, and then save the
mat-file. Then the M-file can continue on without
interaction and produce all my plots, etc.

Could someone help me come up with the code that allows me
to append the X,Y pair to the array?

Thanks!

Re: Help appending entered values to an array

Rodney Thomson — Wed, 23 Jul 2008 03:28:02 -0400

"jeremy " <rower15@excite.com> wrote in message
<g664cp$mjd$1@fred.mathworks.com>...
> I am a rather new user to the MATLAB world and I am having
> some difficulty figuring this out.
>
> I have a mat-file that contains an array of 2 cols and 14
> rows. When this mat-file is loaded, it produces a variable
> called "hc_actual" which is a 14x2 double.
>
> Here's what I want to do...
>
> Add code to my M-file that will allow me to enter a new X,Y
> pair at the command window prompt, append that pair to the
> first empty row in the "hc_actual" array, and then save the
> mat-file. Then the M-file can continue on without
> interaction and produce all my plots, etc.
>
> Could someone help me come up with the code that allows me
> to append the X,Y pair to the array?
>
> Thanks!
>

You can index past the end of the array and Matlab will
dynamically resize it for you:

load hc_actual.mat

hc_actual = rand([14 2]);

new_value = [2.3123 4.6631];

hc_actual(end+1, :) = new_value; % appends to end of
hc_actual - now a 15x2 matrix

save hc_actual

Rod

--
http://iheartmatlab.blogspot.com

Re: Help appending entered values to an array

jeremy — Wed, 23 Jul 2008 18:34:04 -0400

Thanks for the input Rod... Your suggestion worked on the
first try.

Now here's a follow-up...

The first few lines of my file are as follows: