Contour plot legend

[Daniel Kraehmer]

Dear Statalist community,

I have two questions related to the legend of contour plots:

1) Legend width
help clegend_option lists both height() and width() as suboptions. However, only width() seems to affect the rendition of the legend in the example below ("default" and "short" are identical).

* Setup
clear all
macro drop _all
version 17
sysuse sandstone.dta, clear

* Contour plots
twoway contour depth northing easting, name(default)
twoway contour depth northing easting, name(narrow) clegend(width(*0.5))
twoway contour depth northing easting, name(short) clegend(height(*0.5))
twoway contour depth northing easting, name(quickfix) clegend(region(margin(t=10 b=10)))

What am I missing? Compressing the legend by adding margins does the job, but it seems there should be a native solution.

2) Legend positioning
Am I right to assume that there is no way of flipping the clegend (similar to the ramp(bottom) option in Ben Jann's heatplot ado)? My goal ist to add a horizontal color ramp at the bottom of a twoway graph. The closest I got is using contourline as a workaround.

sysuse sandstone.dta, clear
#delimit ;
twoway contourline depth northing easting,
    colorlines crule(intensity) ecolor(dknavy) reversekey
    ccuts(7500(100)8000) format(%0.0f) graphregion(color(white))
    clwidth(vvvthick vvvthick vvvthick vvvthick vvvthick vvvthick)
    plegend(cols(6) pos(6) stack colgap(0) region(lcolor(none)))
;
#delimit cr

(dont't mind the ugly graph; it's all about the legend)

I noticed that Stata 18 offers the colorvar() option but I haven't seen any horizontal color ramps in the official documentation there either. Any ideas and comments are appreciated!

I am using Stata 17 on Windows 10.

[Daniel Kraehmer]

Yet another curiosity I just discovered when working with twoway contourline: The help file (help twoway_contourline) states that option clwidths() takes a linewidthstylelist as input. However, it does not seem to tolerate shorthands:

clear all
macro drop _all
version 17
sysuse sandstone.dta, clear

* Generate help variables
range x 1 10 10
forvalues i = 1/4 {
    gen y`i' = `i'
}

* Shorthand notation: Example 1 (works as expected)
twoway (line y1 y2 y3 y4 x, lwidth(vthick ...) name(g1))

* Shorthand notation: Example 2 (does not work)
twoway contourline depth northing easting, colorlines clwidth(vthick ...) name(g2)

* Stylelist notation without shorthand: Example 3 (works, but is tedious)
twoway contourline depth northing easting, colorlines clwidth(vthick vthick vthick vthick) name(g3)

Sure, I can count the number of lines in my plot and write a loop to repeat the desired lwidth but this seems to be at odds with the idea of linewidthstylelist (and the documentation of twoway contourline).

[Andrew Musau]

* Stylelist notation without shorthand: Example 3 (works, but is tedious)
twoway contourline depth northing easting, colorlines clwidth(vthick vthick vthick vthick) name(g3)

Just use -lwidth()- instead. Not sure that the documentation states that what you want is possible. If that is the case, contact Technical Services.

twoway contourline depth northing easting, colorlines lwidth(vthick) name(g3)

On the contour legend, tw countour only supports a vertical legend.