Next Previous Up Contents
Next: Examples
Up: tcube: N-dimensional Histogram Calculator
Previous: tcube: N-dimensional Histogram Calculator
The usage of tcube
is
stilts <stilts-flags> tcube ifmt=<in-format> istream=true|false icmd=<cmds>
cols=<col-id> ... bounds=[<lo>]:[<hi>] ...
binsizes=<size> ... nbins=<num> ...
out=<out-file> bitpix=8|16|32|64
[in=]<table>
If you don't have the stilts
script installed,
write "java -jar stilts.jar
" instead of
"stilts
" - see Section 3.
The available <stilts-flags>
are listed
in Section 2.1.
Parameter values are assigned on the command line
as explained in Section 2.3.
They are as follows:
-
binsizes = <size> ...
- Gives the extent of of the data bins (cube pixels) in each
dimension in data coordinates.
The form of the value is a space-separated list of values,
giving a list of extents for the first, second, ... dimension.
Either this parameter or the
nbins
parameter
must be supplied.
-
bitpix = 8|16|32|64
- The length in bits of the integer type used for the output
array. If no selection is made, the output type will be
determined automatically as the shortest type required to hold
all the values in the array.
Currently, signed integers are always used (no BSCALE/BZERO),
so for instance the largest value that can be recorded
in 8 bits is 127.
-
bounds = [<lo>]:[<hi>] ...
- Gives the bounds for each dimension of the cube in data
coordinates. The form of the value is a space-separated list
of words, each giving an optional lower bound, then a colon,
then an optional upper bound, for instance
"1:100 0:20" to represent a range for two-dimensional output
between 1 and 100 of the first coordinate (table column)
and between 0 and 20 for the second.
Either or both numbers may be omitted to indicate that the
bounds should be determined automatically by assessing the
range of the data in the table.
A null value for the parameter indicates that all bounds should
be determined automatically for all the dimensions.
If any of the bounds need to be determined automatically
in this way, two passes through the data will be required,
the first to determine bounds and the second
to populate the cube.
-
cols = <col-id> ...
- Columns to use for this task.
One or more
<col-id>
elements,
separated by spaces, should be given.
Each one represents a column in the table, using either its
name or index.
The number of columns listed in the value of this
parameter defines the dimensionality of the output
data cube.
-
icmd = <cmds>
- Commands to operate on the input table,
before any other processing takes place.
The value of this parameter is one or more of the filter commands
described in Section 5.1.
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.
-
ifmt = <in-format>
- Specifies the format of the input table
(one of the known formats listed in Section 4.1).
This flag can be used if you know what format your input
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)
]
-
in = <table>
- The location of the input table.
This is usually a filename or URL, and may point to a file
compressed in one of the supported compression formats
(Unix compress, gzip or bzip2).
If it is omitted, or equal to the special value "-",
the input table will be read from standard input.
In this case the input format must be given explicitly
using the
ifmt
parameter.
-
istream = true|false
- If set true, the
in
table
will be read as a stream.
It is necessary to give the
ifmt
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 input 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
]
-
nbins = <num> ...
- Gives the number of bins (cube pixels) in each dimension.
The form of the value is a space-separated list of integers,
giving the number of pixels for the output cube in the
first, second, ... dimension.
Either this parameter or the
binsizes
parameter
must be supplied.
-
out = <out-file>
- The location of the output file. This is usually a filename
to write to.
If it is equal to the special value "-"
the output will be written to standard output.
The output cube is currently written as a single-HDU FITS file. [Default:
-
]
Next Previous Up Contents
Next: Examples
Up: tcube: N-dimensional Histogram Calculator
Previous: tcube: N-dimensional Histogram Calculator
STILTS - Starlink Tables Infrastructure Library Tool Set
Starlink User Note
256
STILTS web page:
http://www.starlink.ac.uk/stilts/
Author email:
m.b.taylor@bristol.ac.uk