Plots a line through a given quantile of the values binned within each pixel column (or row) of a plot. The line is optionally smoothed using a configurable kernel and width, to even out noise arising from the pixel binning. Instead of a simple line through a given quantile, it is also possible to fill the region between two quantiles.
One way to use this is to draw a line estimating a function y=f(x) (or x=g(y)) sampled by a noisy set of data points in two dimensions.
layerN=quantile colorN=<rrggbb>|red|blue|... transparencyN=0..1 quantilesN=<low-frac>[,<high-frac>] thickN=<pixels> smoothN=+<width>|-<count> kernelN=square|linear|epanechnikov|cos|cos2|gauss3|gauss6 horizontalN=true|false <pos-coord-paramsN> inN=<table> ifmtN=<in-format> istreamN=true|false icmdN=<cmds>
All the parameters listed here
affect only the relevant layer,
identified by the suffix
<pos-coord-paramsN>give a position for each row of the input table. Their form depends on the plot geometry, i.e. which plotting command is used. For a plane plot (
plot2plane) the parameters would be
yN. The coordinate parameter values are in all cases strings interpreted as numeric expressions based on column names. These can be column names, fixed values or algebraic expressions as described in Section 10.
stilts plot2plane in=tgas_source.fits x=phot_g_mean_mag y=phot_g_mean_flux_error ylog=true xmax=15 ymin=10 layer.d=mark color.d=99ff99 layer.q4=quantile quantiles.q4=0.25,0.75 color.q4=magenta transparency.q4=0.35 layer.q2=quantile quantiles.q2=0.5 color.q2=SkyBlue thick.q2=4 smooth.q=0.05 leglabel.q4=Quartiles leglabel.q2=Median legseq=.q4,.q2 legpos=0.95,0.95
colorN = <rrggbb>|red|blue|...(Color)
The standard plotting colour names are
However, many other common colour names (too many to list here)
are also understood.
The list currently contains those colour names understood
by most web browsers,
listed e.g. in the
Extended color keywords section of
the CSS3 standard.
Alternatively, a six-digit hexadecimal number RRGGBB
may be supplied,
optionally prefixed by "
#" or "
giving red, green and blue intensities,
0xff00ff" for magenta.
horizontalN = true|false(Boolean)
true, there is a y value calculated for each pixel column, and if
false, there is an x value for each pixel row.
icmdN = <cmds>(ProcessingStep)
inN. The value of this parameter is one or more of the filter commands described in Section 6.1. If more than one is given, they must be separated by semicolon characters (";"). This parameter can be repeated multiple times on the same command line to build up a list of processing steps. The sequence of commands given in this way defines the processing pipeline which is performed on the table.
Commands may alteratively be supplied in an external file,
by using the indirection character '@'.
Thus a value of "
causes the file
filename to be read for a list
of filter commands to execute. The commands in the file
may be separated by newline characters and/or semicolons,
and lines which are blank or which start with a
#' character are ignored.
ifmtN = <in-format>(String)
inN. The known formats are listed in Section 5.2.1. This flag can be used if you know what format your table is in. If it has the special value
(auto)(the default), then an attempt will be made to detect the format of the table automatically. This cannot always be done correctly however, in which case the program will exit with an error explaining which formats were attempted.
inN = <table>(StarTable)
-", meaning standard input. In this case the input format must be given explicitly using the
ifmtNparameter. Note that not all formats can be streamed in this way.
<" character at the start, or a "
|" character at the end ("
<syscmd" or "
syscmd|"). This executes the given pipeline and reads from its standard output. This will probably only work on unix-like systems.
istreamN = true|false(Boolean)
inNparameter will be read as a stream. It is necessary to give the
ifmtNparameter in this case. Depending on the required operations and processing mode, this may cause the read to fail (sometimes it is necessary to read the table more than once). It is not normally necessary to set this flag; in most cases the data will be streamed automatically if that is the best thing to do. However it can sometimes result in less resource usage when processing large files in certain formats (such as VOTable).
kernelN = square|linear|epanechnikov|cos|cos2|gauss3|gauss6(Kernel1dShape)
The available options are:
square: Uniform value: f(x)=1, |x|=0..1
linear: Triangle: f(x)=1-|x|, |x|=0..1
epanechnikov: Parabola: f(x)=1-x*x, |x|=0..1
cos: Cosine: f(x)=cos(x*pi/2), |x|=0..1
cos2: Cosine squared: f(x)=cos^2(x*pi/2), |x|=0..1
gauss3: Gaussian truncated at 3.0 sigma: f(x)=exp(-x*x/2), |x|=0..3
gauss6: Gaussian truncated at 6.0 sigma: f(x)=exp(-x*x/2), |x|=0..6
quantilesN = <low-frac>[,<high-frac>](Subrange)
<lo>,<hi>) indicating two quantile lines bounding an area to be filled. A pair of equal values "
a,a" is equivalent to the single value "
a". The default is
0.5, which means to mark the median value in each column, and could equivalently be specified
smoothN = +<width>|-<count>(BinSizer)
If the supplied value is a positive number it is interpreted as a fixed width in the data coordinates of the X axis (if the X axis is logarithmic, the value is a fixed factor). If it is a negative number, then it will be interpreted as the approximate number of smooothing widths that fit in the width of the visible plot (i.e. plot width / smoothing width). If the value is zero, no smoothing is applied.
When setting this value graphically, you can use either the slider to adjust the bin count or the numeric entry field to fix the bin width.
thickN = <pixels>(Integer)
quantilesspecifies a single value rather than a pair) this will give the actual thickness of the plotted line. If the range is non-zero however, the line may be thicker than this in places according to the quantile positions.
transparencyN = 0..1(Double)