plot2time: Draws a time plot
plot2time draws plots where the horizontal axis represents time.
The time axis can be labelled in various different ways including
MJD, decimal year and ISO-8601 form.
Positional coordinates are specified as
with an optional
ttype specifier to indicate how the
input value is to be interpreted,
plot2time in1=series.fits layer1=line t1=EPOCH ttype1=MJD y1=ENERGY
Time values can be represented in various ways in input data,
for instance as Julian Day, Modified Julian Date, decimal years
since 0AD, Unix seconds, ISO-8601, or variants of some of the
above with additional offsets.
In some cases the input format contains enough metadata to
determine how the values should be mapped to a common timescale
(so for instance they can be plotted as MJD or Year/Month/Day),
and in other cases they do not.
For example CDF files and VOTable 1.4 files with
markup contain sufficient metadata, and text inputs using the
ISO-8601 format can usually be identified and understood,
but there's no way to tell automatically whether a numeric column
in a CSV file represents MJD, seconds since a known epoch,
decimal years, or anything else.
For this reason the
ttypeN parameter is provided
for all the layer types with a
ttypeN = DecYear|MJD|JD|Unix|Iso8601 (TimeMapper)
tN is supplied.
DecYear: Years since 0 AD
MJD: Modified Julian Date
JD: Julian Day
Unix: Seconds since midnight 1 Jan 1970
Iso8601: ISO 8601 string
unlike the other
plot2* commands at time of writing,
can be used to draw multi-zone plots.
These are plots with different panels stacked vertically so that
different datasets can share the same horizontal (time) axis, but have
separate vertical axes, colour maps, legends etc.
The horizontal axes are always synchronized between zones.
This is currently controlled with the
For any layer with a layer suffix
N, you can specify
a zone identifier as an arbitrary string,
by supplying the parameter
Layers with the same value of
zoneN are plotted in the same zone, and layers with
different values are plotted in different zones.
zoneN is given, the layer is assigned to
a single (unnamed) zone, so with no zone parameters specified
all plots appear in a single zone.
Parameters specific to a given zone can then be suffixed with the
Z zone identifier.
The examples section illustrates
what this looks like in practice.
Note: The multi-zone feature is experimental. As currently implemented it lacks some features. The interface may be changed in a future version.
Content is added to the plot by specifying
one or more plot layers using the
N part is a suffix applied to
all the parameters affecting a given layer;
any suffix (including the empty string) may be used.
Available layers for this plot type are: