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How to omit zero value line in contourm figure

Asked by chia hua

chia hua (view profile)

on 26 May 2013

Hi I want to have a contour plot without zero value line,

I have been search internet and matlab Q&A for a long time,

but can't find answer , how can I do this ?

P.S. I know contour plot can give the line interval you want to avoid zero line,but I have several figures and each one has different scale, so is there any method to omit zero line after you draw the figure ?

thank you

this is my figure link

https://docs.google.com/file/d/0BxUY6-ywKIvpUjF5VlIwZFU0VkU/edit?usp=sharing

2 Comments

your image is a raster (pictorios) or vector?

chia hua

chia hua (view profile)

on 26 May 2013
set(gcf,'PaperPositionMode','auto') 
set(hFig, 'Position', [350 200 800 800]) axesm ('stereo','Grid', 'off','MapLatLimit',[ys 90],'Origin',[90 120 0],'Frame','on','FLineWidth',2,... 'MeridianLabel','off','MLabelParallel','south','LabelRotation','off'); 
axis off 
load coast 
plotm(lat, long,'k-','color',[0.4,0.4,0.4],'LineWidth',1) 
projn=[reco,reco(:,1)]; 
hold on 
[C,h]=contourm(yy,[xx,360],projn,'k-','LineWidth',1,'LevelStep',int);

this is my code , I think it is vector..?

xx,yy : grid

projn : data

chia hua

chia hua (view profile)

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1 Answer

Answer by Walter Roberson

Walter Roberson (view profile)

on 26 May 2013
Accepted answer

Yes, it is possible to remove the 0 contour after drawing... and what if there is no contour at exactly 0 because your "int" steps ended up with the closest division being at (say) -1/10? Or -5000 depending on the scale of the data.

You are better of figuring out exactly where you want the contours, and providing that list of levels as the argument after "projn" in your call. That way you could figure out how big you want your steps to be, and you could round() the levels to "nice numbers" using what-ever algorithm you liked, and you could decide whether you just want the 0 deleted (leaving a double-width near 0) or if you want to instead center the equal-sized steps so that 0 is in the middle between two steps.

0 Comments

Walter Roberson

Walter Roberson (view profile)

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