topic Re: Density axis: How to access it in the Distribution platform (i.e. histogram)? in Discussions

Density axis: How to access it in the Distribution platform (i.e. histogram)?

scottahindle — Mon, 02 Dec 2019 15:55:41 GMT

I commonly add text onto graphs using "Add graphics script". I prefer to script it which means specifying x and y coordinates so the text appears in a good place on the graph.

I am stuck with histograms (in the Distribution platform) because I don't know how to get the y-axis scale which is based on the density axis. The x-axis is easy enough - it is based on the original data - but I need both x and y for my added text to appear in a meaningful place.

An example simple script is:

dist = Distribution(
	Continuous Distribution( Column( :C1 ), Horizontal Layout( 1 ), Vertical( 0 ) ),
	Histograms Only
);

rdist = dist << report; // rdist << Show Tree Structure;

axis_box = rdist[axis box( 1 )];
x_max = axis_box << Get Max; // show(x_max);

framebox = rdist[frame box( 1 )];
framebox << Add Graphics Script(
	Text Color( "red" );
	Text( Center Justified, {0.98 * x_max, 0.4}, "centered" ); // 0.4 is the y-value, but how to know the density axis scale?
);

Can anybody help? i.e. how to access details of the histogram's density axis so I can get the relevant information and then script where my desired text appears on the graph?

Re: Density axis: How to access it in the Distribution platform (i.e. histogram)?

txnelson — Wed, 27 Nov 2019 23:01:11 GMT

If you specify to turn on the Density Axis for the histogram, you can access the Axis Settings for Axis Box(2)

dist=Distribution( Continuous Distribution( Column( :height ), Density Axis( 1 ) ) );

report(dist)[AxisBox(2)]<<get max;

Re: Density axis: How to access it in the Distribution platform (i.e. histogram)?

scottahindle — Mon, 02 Dec 2019 15:56:19 GMT

Thanks for the hint.

I turn on the density access at the start of the script so I can pull the min/max values.

Once these values are in the list - that will lead me to the coordinates I need - I simply remove the density access from the display:

dist << density axis(0);

Thanks again, Scott.