Better control of error bars from Python

[Nick Draper]

From qtiplot handbook:

Error Bars

Having a plot layer l, you can add error bars to a data curve c, named curveName, using the following methods:

err1 = l.addErrorBars(c, Table *t, QString errColName, int type = 1, double width = 1, int capLength = 8, color = Qt.black, throughSymbol = True, minusSide = True, plusSide = True)
err2 = l.addErrorBars(curveName, Table *t, QString errColName, int type = 1, double width = 1, int capLength = 8, color = Qt.black, throughSymbol = True, minusSide = True, plusSide = True)
Each data curve, c, can have attached a list of error bars:

errors = c.errorBarsList()
The properties of an error bar curve can be accesses, via the following methods:

err = c.errorBarsList()[0]
for i in range(0, err.dataSize()):
	print err.errorValue(i)

err.capLength()
err.width()
err.color()
err.direction()
err.xErrors()
err.throughSymbol()
err.plusSide()
err.minusSide()
c = err.masterCurve() # reference to the master curve to which the error bars curve is attached.
err.detachFromMasterCurve() # equivalent to c.removeErrorBars(err)
... and can be modified, via the following methods:

err.setCapLength(12)
err.setWidth(3)
err.setColor(Qt.red)
err.setDirection(ErrorBarsCurve.Vertical)
err.setXErrors(True) # equivalent to err.setDirection(ErrorBarsCurve.Horizontal)
err.drawThroughSymbol(True)
err.drawPlusSide(True)
err.drawMinusSide(False)
err.setMasterCurve(c)
You can remove all error bars attached to a curve using:

c.clearErrorBars()

[Nick Draper]

Bulk move of tickets at the end of iteration 28

[Nick Draper]

"New" tickets moved at the code freeze of iteration 29

[Nick Draper]

Bulk move of tickets to iteration 31 at the iteration 30 code freeze

[Russell Taylor]

The thing that stops this being trivial is that we handle error bars for 'Mantid curves' completely differently to QtiPlot. In the latter, the errors are stored in a completely separate 'PlotCurve' specialisation - which then has all the methods referred to above. For us, it's all within the 'MantidCurve'.

Maybe the answer is to have a common interface which holds all these settings, use that for each type of curve and expose that to python.

[Russell Taylor]

Add class holding settings for error bars. Re #2657.

Very simple class of attributes and getters & setters, pulled out of QwtErrorPlotCurve.

Changeset: ad3d3b394c03287e90f1f01e5c159aa6a4523141

[Russell Taylor]

Expose ErrorBarSettings to python. Re #2657.

Changeset: 14cddb6ceb9fb63a405d1c698c8a1000bd7780d7

[Russell Taylor]

Add methods to get error bar settings for a curve. Re #2657.

Although a Mantid curve's error bar settings can be accessed, they aren't applied yet.

Changeset: cb26d897c2e3e85177d7185366dd204cf6bd0bd7

[Russell Taylor]

Indentation changes only. Re #2657.

Changeset: b1ca7c5b30490153091cf1ba105e76817c25460d

[Russell Taylor]

MantidCurves now take notice of error bar settings. Re #2657.

Though they can only be customised from python at the moment, and are not retained on saving a project.

Changeset: 20b8bc4f94edaf6de59dcec85eef63fef327ece7

[Russell Taylor]

Try to fix unixy places. Re #2657.

Changeset: fc62f35ca29e162b40a140bf03ee086955dfacc5

[Nick Draper]

Moved to iteration 33 at iteration 32 code freeze

[Russell Taylor]

Just need to write the wiki documentation.

[Russell Taylor]

Documentation is at: http://www.mantidproject.org/MantidPlot:_Error_Bars

Follow-up ticket #4469 has been created to improve Mantid curve error bars in general in MantidPlot.

[Nick Draper]

passed testing

[Stuart Campbell]

This ticket has been transferred to github issue ​3504