From help-octave-request at bevo dot che dot wisc dot edu Mon Mar 22 09:15:15 2004
Subject: Re: partial plot
From: Miquel Cabanas <Miquel dot Cabanas at uab dot es>
To: "Pascal A. Dupuis" <Pascal dot Dupuis at esat dot kuleuven dot ac dot be>
Cc: Octave_post <help-octave at bevo dot che dot wisc dot edu>
Date: Mon, 22 Mar 2004 16:10:35 +0100

ok, that requieres a bit of octave code to handle the situation

On Fri, Mar 19, 2004 at 02:11:08PM -0600, Pascal A. Dupuis wrote:
> 
> In the case of NaN, the value is ignored, and lines are interpolated
> around the missing point. What I would like is to have the line stop
> before the missing value, to emphasize the fact that nothing is available.
> 

i think the code below will work, otherwise feel free to modify
and/or improve it to fit your needs. So far I have tested having
NaN at one or both ends, having consecutive NaN, and nothing crashed,
but in some cases x_to_plot and y_to_plot were equal to "[](0x0)",
though nothing wrong happened.

y = [10, -20, NaN, -40, 50, NaN, 70, -80];
x = 1:1:length(y);

## create a vector that will hold the discontinuities,
## i.e. NaN's indices
discontin = find(isnan(y))
if !isnan(y(1))
  ## first point is a number, pretend there's a NaN at #0
  discontin = [0, discontin]
endif
if !isnan(y(length(y)))
  ## last point is a number, pretend there's a NaN past the end
  discontin = [discontin,length(y)+1]
endif

figure();
hold on;

for i=1:length(discontin)-1
  ## create subvector to plot
  x_to_plot = x(discontin(i)+1:discontin(i+1)-1)
  y_to_plot = y(discontin(i)+1:discontin(i+1)-1)
    
  ## plot data
  plot(x_to_plot, y_to_plot, 'o-')
endfor


Briefly, in the above case,  discontin = [3 6]  in a first instance,
and then  discontin = [0 3 6 9]  after adding the fake NaN that limit
the edges of y-vector. The plotted subvectors are  y(1,2), y(4,5) and
y(7,8).


Hope this helps,


Miquel


-- 
Miquel E Cabanas ------------------------------------------------------
SeRMN, Universitat Autonoma de Barcelona (Miquel dot Cabanas at uab dot es)
------------------------------------------o-oo--ooo---ooo--oo-o--------



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