Problem with DateHistogram Epilog

Mathematica Asked on June 11, 2021

Bug introduced in 11.3 or earlier and persisting through 12.3.0

@Szabolcs reported this bug on the WRI Redmine bug tracker 11 months ago. It is still "In Progress".

Epilog in DateHistogram is incorrectly rendered.

$Version
(* "12.2.0 for Mac OS X x86 (64-bit) (December 12, 2020)" *)    

dates = {DateObject[{2021, 01, 10}], DateObject[{2021, 01, 10}], DateObject[{2021, 01, 12}]}

epilog = Inset[Framed[Grid[{{"Mean", 1.5}}, Alignment -> {{Left, Right}}]], Scaled[{1, 1}], ImageScaled[{1, 1}]];

The epilog looks fine

Graphics@epilog

When it is used in DateHistogram, AbsoluteTime is evaluated on the text.

DateHistogram[dates, "Day", Epilog -> epilog]

Reproducible on Wolfram Cloud "12.2.0 for Linux x86 (64-bit) (November 16, 2020)"

This only happens with DateHistogram, it works fine with Histogram. I could find nothing in the documentation regarding the special behavior of Epilog in DateHistogram.

Is this a bug? Any workarounds?

bugs date and time histograms

One Answer

This is certainly a bug: All pairs {a:(_String|_List), b_?(NumberQ[N@#]&)} that appear anywhere in epilog/prolog are replaced with {AbsoluteTime[a], b}.

An example that shows various cases that trigger the mysterious behavior as well as possible work-arounds:

epilog2 = Inset[Framed[
    Grid[{{"FOO", 1.5}, 
        {"FOO", BAR[1.5]},
        {"FOO", "1.5"}, 
        {Defer@"FOO", 1.5},
        {FOO, 1.5},
        {{2021, 1, 1}, 1.5}, 
        {{2021, 1, 1}, "1.5"},
        {{2021, 1, 1}, 1.5, ""},
        {Defer@{2021, 1, 1}, 1.5}
        {{100}, 1.5},
        {Defer@{100}, 1.5}}, 
   Alignment -> {{Left, Right}}]], Scaled[{1, 1}],  ImageScaled[{1, 1}]];

DateHistogram[dates, "Day", Epilog -> epilog2]

$Version

 "11.3.0 for Microsoft Windows (64-bit) (March 7, 2018)"

An alternative work-around is to remove the option Epilog from DateHistogram, wrap it with Show and add the epilog in Show:

Show[DateHistogram[dates, "Day",  ImageSize -> Large], Epilog -> epilog2]

Show[DateHistogram[dates, "Day",  ImageSize -> Large], Graphics@epilog2]

The culprit is the replacement rule Charting`timeCoordRule applied to epilog (also prolog and axes origin) expressions inside the function Charting`iDateHistogram:

epilog2 /. Charting`timeCoordRule

Its definition:

GeneralUtilities`PrintDefinitionsLocal[Charting`timeCoordRule]

Answered by kglr on June 11, 2021

Add your own answers!

Ask a Question

Get help from others!

Recent Answers

haakon.io on Why fry rice before boiling?
Lex on Does Google Analytics track 404 page responses as valid page views?
Joshua Engel on Why fry rice before boiling?
Jon Church on Why fry rice before boiling?
Peter Machado on Why fry rice before boiling?