densogram
Represents smoothed density of data values along the horizontal axis using a colourmap. This is like a Kernel Density Estimate (smoothed histogram with bins 1 pixel wide), but instead of representing the data extent vertically as bars or a line, values are represented by a fixed-size pixel-width column of a colour from a colour map. A smoothing kernel, whose width and shape may be varied, is applied to each data point.
This is a rather unconventional way to represent density data, and this plotting mode is probably not very useful. But hey, nobody's forcing you to use it.
Usage Overview:
layerN=densogram colorN=<rrggbb>|red|blue|... smoothN=+<width>|-<count> kernelN=square|linear|epanechnikov|cos|cos2|gauss3|gauss6 densemapN=inferno|magma|plasma|... denseclipN=<lo>,<hi> denseflipN=true|false densequantN=<number> densefuncN=log|linear|sqrt|square densesubN=<lo>,<hi> cumulativeN=true|false sizeN=<pixels> posN=<fraction> xN=<num-expr> weightN=<num-expr> inN=<table> ifmtN=<in-format> istreamN=true|false icmdN=<cmds>
All the parameters listed here
affect only the relevant layer,
identified by the suffix
N
.
colorN = <rrggbb>|red|blue|...
(Color)
The value may be a six-digit hexadecimal number
giving red, green and blue intensities,
e.g. "ff00ff
" for magenta.
Alternatively it may be the name of one of the
pre-defined colors.
These are currently
red
, blue
, green
, grey
, magenta
, cyan
, orange
, pink
, yellow
, black
, light_grey
, white
.
[Default: red
]
cumulativeN = true|false
(Boolean)
[Default: false
]
denseclipN = <lo>,<hi>
(Subrange)
If the full range 0,1
(the default) is used,
the whole range of colours specified by the selected
shader will be used.
But if, for instance a value of 0,0.5
is given,
only those colours at the left hand end of the ramp
will be seen.
[Default: 0,1
]
denseflipN = true|false
(Boolean)
[Default: false
]
densefuncN = log|linear|sqrt|square
(Scaling)
The available options are:
log
: Logarithmic scalinglinear
: Linear scalingsqrt
: Square root scalingsquare
: Square scaling[Default: linear
]
densemapN = inferno|magma|plasma|...
(Shader)
A mixed bag of colour ramps are available:
inferno
,
magma
,
plasma
,
viridis
,
cubehelix
,
sron
,
rainbow
,
rainbow2
,
rainbow3
,
pastel
,
accent
,
gnuplot
,
gnuplot2
,
specxby
,
set1
,
paired
,
hotcold
,
rdbu
,
piyg
,
brbg
,
cyan-magenta
,
red-blue
,
brg
,
heat
,
cold
,
light
,
greyscale
,
colour
,
standard
,
bugn
,
bupu
,
orrd
,
pubu
,
purd
,
huecl
,
hue
,
intensity
,
rgb_red
,
rgb_green
,
rgb_blue
,
hsv_h
,
hsv_s
,
hsv_v
,
yuv_y
,
yuv_u
,
yuv_v
,
scale_hsv_s
,
scale_hsv_v
,
scale_yuv_y
,
mask
,
blacker
,
whiter
,
transparency
.
Note:
many of these, including rainbow-like ones,
are frowned upon by the visualisation community.
[Default: inferno
]
densequantN = <number>
(Double)
If left blank, the colour map is nominally continuous (though in practice it may be quantised to a medium-sized number like 256).
densesubN = <lo>,<hi>
(Subrange)
The default value "0,1
" therefore has
no effect.
The range could be restricted to its lower half
with the value 0,0.5
.
[Default: 0,1
]
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 "@filename
"
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.
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.
[Default: (auto)
]
inN = <table>
(StarTable)
-
",
meaning standard input.
In this case the input format must be given explicitly
using the ifmtN
parameter.
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)
inN
parameter
will be read as a stream.
It is necessary to give the
ifmtN
parameter
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).
[Default: false
]
kernelN = square|linear|epanechnikov|cos|cos2|gauss3|gauss6
(Kernel1dShape)
The available options are:
square
: Uniform value: f(x)=1, |x|=0..1linear
: Triangle: f(x)=1-|x|, |x|=0..1epanechnikov
: Parabola: f(x)=1-x*x, |x|=0..1cos
: Cosine: f(x)=cos(x*pi/2), |x|=0..1cos2
: Cosine squared: f(x)=cos^2(x*pi/2), |x|=0..1gauss3
: Gaussian truncated at 3.0 sigma: f(x)=exp(-x*x/2), |x|=0..3gauss6
: Gaussian truncated at 6.0 sigma: f(x)=exp(-x*x/2), |x|=0..6[Default: epanechnikov
]
posN = <fraction>
(Double)
[Default: 0.05
]
sizeN = <pixels>
(Integer)
[Default: 12
]
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.
[Default: -100
]
weightN = <num-expr>
(String)
The value is a numeric algebraic expression based on column names as described in Section 10.
xN = <num-expr>
(String)
The value is a numeric algebraic expression based on column names as described in Section 10.