Question on IF statements, I think...

jeremy — Wed, 23 Jul 2008 18:50:04 -0400

I've got the following code which is doing almost just what
I want it to do...

   load HC_actual;
   New_measurement = input('Enter new x/y data pair: ');
   HC_Chart_actual(end+1,:) = New_measurement;
   save HC_actual

Now for the question... How do I put the above code in my
M-file so that I can, from the command prompt, opt to enter
new data or just go on with the M-file without adding new
data to the HC_actual array?

Basically, I want a Command Window prompt that asks "Do you
want to enter new data?" and depending on whether I type in
'y' or 'n', the program either does the above code or skips
the code and continues the routine.

Any suggestions?

Thanks! Jeremy

Re: Question on IF statements, I think...

roberson@ibd.nrc-cnrc.gc.ca (Walter Roberson) — Wed, 23 Jul 2008 19:01:05 -0400

In article <g67ugs$6bl$1@fred.mathworks.com>,
jeremy <rower15@excite.com> wrote:
>I've got the following code which is doing almost just what
>I want it to do...

> load HC_actual;

I would suggest that you get used to using the function form of load:
Matlab can do much better optimization if it doesn't have to deal with
variables in the workspace suddenly popping into existance.
You cannot (easily) use the command version of 'load' if you
are using nested functions for example.

> New_measurement = input('Enter new x/y data pair: ');
> HC_Chart_actual(end+1,:) = New_measurement;
> save HC_actual

>Now for the question... How do I put the above code in my
>M-file so that I can, from the command prompt, opt to enter
>new data or just go on with the M-file without adding new
>data to the HC_actual array?
>
>Basically, I want a Command Window prompt that asks "Do you
>want to enter new data?" and depending on whether I type in
>'y' or 'n', the program either does the above code or skips
>the code and continues the routine.

HC_struct = load('HC_actual.mat');
if ~isfield(HC_struct, 'HC_Chart_actual')
  error('Corrupt HC_actual file!');
end

addsomething = input('Do you want to enter new data? Y/[N]', 's');
if ~isempty(addsomething) && strcmpi(strtrim(addsomething),'y')
  New_measurement = input('Enter new x/y data pair: ');
  HC_struct.HC_Chart_actual(end+1,:) = New_measurement;
  save('HC_actual.mat', 'HC_struct', '-struct');
end

This code assumes that, either way, you will want HC_Chart_actual
in your workspace after the section of code. If you don't need
HC_Chart_actual unless the user wants to update it, then
you can move the load() call and associated sanity check
inside of the if statement.
--
  "Ignorance has been our king... he sits unchallenged on the throne of
  Man. His dynasty is age-old. His right to rule is now considered
  legitimate. Past sages have affirmed it. They did nothing to unseat
  him." -- Walter M Miller, Jr

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