Specify intervals between data

evan · Post by **evan** » Wed Mar 14, 2007 10:03 am

Hi,

I'm a new user of this software, and would like to know how do I do the following in DPlot:

e.g. I have 1,000,000 points on x-y plane, instead drawing all of these points, I'd like to be able to draw every 10th (based on x-axis) points only, i.e. draw only when x = 10, 20, 30,.....1,000,000, and every other points in between should be ignored.

Is this possible in DPlot? If so, where can I specify this interval for drawing the graph? Many thanks.
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Post by **DPlotAdmin** » Wed Mar 14, 2007 10:20 am

Is this possible in DPlot?

If the points are evenly spaced in X, yes. If they are, then click the Line/Symbol Styles button or select Symbol/Line Styles on the Options menu. In the lower left corner you'll see a Symbol Frequency entry. 1=draw every symbol, 2=draw every other symbol, 3=draw every 3rd symbol, etc.

If your data is not evenly spaced in X then you can still do this after manipulating the data a bit. Select Edit>Equal Intervals, enter the interval you want in X and select Linear under Interpolation. Then repeat the above.

evan · Post by **evan** » Wed Mar 14, 2007 10:30 am

DPlotAdmin wrote:
Is this possible in DPlot?
If the points are evenly spaced in X, yes. If they are, then click the Line/Symbol Styles button or select Symbol/Line Styles on the Options menu. In the lower left corner you'll see a Symbol Frequency entry. 1=draw every symbol, 2=draw every other symbol, 3=draw every 3rd symbol, etc.

If your data is not evenly spaced in X then you can still do this after manipulating the data a bit. Select Edit>Equal Intervals, enter the interval you want in X and select Linear under Interpolation. Then repeat the above.

Thanks.

Yea, I was playing around with it and found out you can do this using "Symbol Frequency" option just a few mins ago.

Another quick question though, I've tried using Scatter Plot fuction, and by default, it draws some 3D-like scatter graph based on the intensity (I'm just guessing here) of the distribution of the data. My question is, can I turn off this 3-d thingy, plus is there any way I can configure a scatter plot? I read in the help file, it says you could adjust the view angles, etc, but I cannot find it in option menu. Thanks a lot.
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Post by **DPlotAdmin** » Wed Mar 14, 2007 10:37 am

Another quick question though, I've tried using Scatter Plot fuction, and by default, it draws some 3D-like scatter graph based on the intensity (I'm just guessing here) of the distribution of the data. My question is, can I turn off this 3-d thingy, plus is there any way I can configure a scatter plot? I read in the help file, it says you could adjust the view angles, etc, but I cannot find it in option menu. Thanks a lot.

If you're talking about the Scatter Plot command on the Options menu, there's nothing 3D about that. That command simply turns on symbols at each data point and sets the line style to "None". This command was recently added in an effort to eliminate "How do I make a scatter plot?" e-mails, where the user wanted to do what was just described. Apparently I've now added another layer of confusion

If you want a 3D scatter plot you need 3D data: X,Y,Z.

evan · Post by **evan** » Wed Mar 14, 2007 10:42 am

So it basically means the options available for a scatter plot are limited now apart from choosing different symbols for each data point. Is that right?
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Post by **DPlotAdmin** » Wed Mar 14, 2007 11:01 am

I'm not sure I understand your question, but see if this helps:

A scatter plot in the context you're talking about is just a 2D XY plot with symbols drawn at each data point. All options that are available with any XY plot are still available with this plot. But there aren't any 3D options (like view angles) because there's no 3rd dimension.

A 3D scatter plot is completely different. It is produced from 3D data and will show different options and different menu commands from XY plots.

Maybe if you could describe what you're trying to do?

evan · Post by **evan** » Wed Mar 14, 2007 11:29 am

DPlotAdmin wrote:I'm not sure I understand your question, but see if this helps:

A scatter plot in the context you're talking about is just a 2D XY plot with symbols drawn at each data point. All options that are available with any XY plot are still available with this plot. But there aren't any 3D options (like view angles) because there's no 3rd dimension.

A 3D scatter plot is completely different. It is produced from 3D data and will show different options and different menu commands from XY plots.

Maybe if you could describe what you're trying to do?

Sorry for the confusion made. I thought the scatter plot draws some 3d-like image because the points get stacked onto each other (I suppose this is the case when there are too many points in a small area), so they look like 'tubes' with different lengths coming out x-y plane to me. See example below:

I was wondering if there is any way to get rid of those 'shadow' of the points. Thanks.
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Post by **DPlotAdmin** » Wed Mar 14, 2007 1:43 pm

I was wondering if there is any way to get rid of those 'shadow' of the points.

Those dark areas are overlapped symbols where you have repeating Y values at successive X's. You can get rid of the dark appearance by selecting Symbol/Line Styles on the Options menu and unchecking the "Outline solid symbols" box. That only gets rid of one problem and presents another, though: instead of black areas you'll get a colored blob. If you want to show all those points then the only suggestion I have is to use smaller symbols.