Qwt Side-bySide bar charts/graphs

[bwnicewo]

Is there any way in Qwt v5.2.1 to do side by side bar graphs with multiple sets of data colored differently to distinguish between the two? I'm trying to be specific in my question as possible. I'm right now using a HistogramItem but there is no way (that I know of) to attach more than one HistogramItem to a QwtPlot without upgrading to v.6.0.1 and using QwtBarItem and using that.

[Uwe]

In fact you would need to upgrade to SVN trunk ( 6.1 ), where you find a QwtPlotMultiBarChart item. Its "Grouped" ( in opposite to "Stacked" ) mode should be what you are looking for. Check the barchart example.

The redesign made in Qwt 6.0 was to primarily to make it possible to introduce new types of plot items - without having to duplicate too much code - and Qwt 6.1 will be the release that introduces them.

Uwe

PS1: I remember there was once ( years ago ) a patch for Qwt 5.x ( or even maybe Qwt 4.x ) - maybe you find it in the mailing list archive.
PS2: Stay away from QwtPlotBarChart - its implementation is not finished.

[bwnicewo]

I'll certainly look into it. I'm still using a HistogramItem for plotting a single data set right now, and that uses a QwtIntervalData class to pass in the data using the setData function, would that still be possible, or would that have to be "wrapped" into another class somehow?

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Added after 23 minutes:

...and is there documentation for it somewhere?

[Uwe]

The plot items are organized according to the type of the samples:

• QwtPlotHistogram
  x -> [y1, y2]
• QwtPlotMultiBarChart
  [ x] -> [ y1, ... yn ] ( or the index in the list is used as x value )
• QwtPlotBarChart
  x - > y ( or the index in the list is used as x value )

QwtPlotHistogram ( more or less the HistogramItem from the Qwt 5 example ) is available since Qwt 6.0. The bar charts item needed some extra work in the framework, because the width of the bars doesn't depend on any coordinates but affects the layout.

Uwe

[bwnicewo]

so there is no docs for it yet?

[Uwe]

so there is no docs for it yet?

http://qwt.sourceforge.net/class_qwt...histogram.html

For the new classes in trunk you have to run doxygen yourself, but I don't have everything written yet. But simply check the barchart example - I don't believe, that you need much docs for using these classes. Probably the most difficult part is to identify the APIs inherited from the base classes.

Uwe

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[Uwe]

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