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#### 8.3.20 `statline`

Plots a single line based on a combination (typically the mean) of input array-valued coordinates. The input X and Y coordinates must be fixed-length arrays of length N; a line with N points is plotted, each point representing the mean (or median, minimum, maximum, ...) of all the input array elements at the corresponding position.

Note that because the X and Y arrays must be of a fixed size for all rows, and because combination is performed in both X and Y directions, this is typically only suitable for plotting combined spectra if they all share a common horizontal axis, e.g. are all sampled into the same wavelength bins. To visually combine spectra with non-uniform sampling, the arrayquantile plotter may be more useful.

Usage Overview:

       layerN=statline xcombineN=mean|median|min|max|q.01|...
                       ycombineN=mean|median|min|max|q.01|...
                       colorN=<rrggbb>|red|blue|... thickN=<pixels>
                       antialiasN=true|false xsN=<array-expr> ysN=<array-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`.

Example:

       stilts plot2plane in=LRS_NPW_V010_20071101.cdf xs=multiply(param$frequency,1e-6) ys=RX2
                         xlabel=f/MHz ylabel=RX2/dB xmin=0.7 xmax=2.0 icmd='select rx2[71]<-170' xpix=700
                         layer1=lines color1=cyan
                         layer2=statline color2=red thick2=3

`antialiasN = true|false` (Boolean)
  If true, plotted lines are drawn with antialising. Antialised lines look smoother, but may take perceptibly longer to draw. Only has any effect for bitmapped output formats.

  [Default: `false`]

`colorN = <rrggbb>|red|blue|...` (Color)
  The color of plotted data, given by name or as a hexadecimal RGB value.

  The standard plotting colour names are `red`, `blue`, `green`, `grey`, `magenta`, `cyan`, `orange`, `pink`, `yellow`, `black`, `light_grey`, `white`. 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, from `AliceBlue` to `YellowGreen`, 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 "`0x`", giving red, green and blue intensities, e.g. "`ff00ff`", "`#ff00ff`" or "`0xff00ff`" for magenta.

  [Default: `red`]

`icmdN = <cmds>` (ProcessingStep[])
  Specifies processing to be performed on the layer N input table as specified by parameter `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 alternatively 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, and lines which are blank or which start with a '`#`' character are ignored. A backslash character '`\`' at the end of a line joins it with the following line.

`ifmtN = <in-format>` (String)
  Specifies the format of the input table as specified by parameter `inN`. The known formats are listed in Section 5.1.1. 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. This parameter is ignored for scheme-specified tables.

  [Default: `(auto)`]

`inN = <table>` (StarTable)
  The location of the input table. This may take one of the following forms:
  - A filename.
  - A URL.
  - The special value "`-`", 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.
  - A scheme specification of the form `:<scheme-name>:<scheme-args>`.
  - A system command line with either a "`<`" 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.
  In any case, compressed data in one of the supported compression formats (gzip, Unix compress or bzip2) will be decompressed transparently.
`istreamN = true|false` (Boolean)
  If set true, the input table specified by the `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). This parameter is ignored for scheme-specified tables.

  [Default: `false`]

`thickN = <pixels>` (Integer)
  Thickness of plotted line in pixels.

  [Default: `3`]

`xcombineN = mean|median|min|max|q.01|...` (Combiner)
  Defines how corresponding array elements on the X axis are combined together to produce the plotted value.

  The available options are:

  - `mean`: the mean of the combined values
  - `median`: the median
  - `min`: the minimum of all the combined values
  - `max`: the maximum of all the combined values
  - `q.01`: 1st percentile
  - `q1`: first quartile
  - `q3`: third quartile
  - `q.99`: 99th percentile
  - `stdev`: the sample standard deviation of the combined values
  - `sum`: the sum of all the combined values per bin
  - `count`: the number of non-blank values per bin (weight is ignored)

  [Default: `mean`]

`xsN = <array-expr>` (String)
  Array giving the X coordinate array for each line. In most cases, if a blank value is supplied but Y values are present then a suitable linear sequence, of the same length as the Y array, is assumed.

  The value is an array-valued algebraic expression based on column names as described in Section 10. Some of the functions in the Arrays class may be useful here.

`ycombineN = mean|median|min|max|q.01|...` (Combiner)
  Defines how corresponding array elements on the Y axis are combined together to produce the plotted value.

  The available options are:

  - `mean`: the mean of the combined values
  - `median`: the median
  - `min`: the minimum of all the combined values
  - `max`: the maximum of all the combined values
  - `q.01`: 1st percentile
  - `q1`: first quartile
  - `q3`: third quartile
  - `q.99`: 99th percentile
  - `stdev`: the sample standard deviation of the combined values
  - `sum`: the sum of all the combined values per bin
  - `count`: the number of non-blank values per bin (weight is ignored)

  [Default: `mean`]

`ysN = <array-expr>` (String)
  Array giving the Y coordinate array for each line. In most cases, if a blank value is supplied but X values are present then a suitable linear sequence, of the same length as the X array, is assumed.

  The value is an array-valued algebraic expression based on column names as described in Section 10. Some of the functions in the Arrays class may be useful here.

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STILTS - Starlink Tables Infrastructure Library Tool Set
Starlink User Note256
STILTS web page: http://www.starlink.ac.uk/stilts/
Author email: m.b.taylor@bristol.ac.uk
Mailing list: topcat-user@jiscmail.ac.uk