DESCRIPTION¶
tcatn is a tool for concatenating a number of tables one
after the other. Each table can be manipulated separately prior to the
concatenatation. If you have two tables T1 and T2 which contain similar
columns, and you want to treat them as a single table, you can use
tcatn to produce a new table whose metadata (row headings etc) comes
from T1 and whose data consists of all the rows of T1 followed by all the
rows of T2.
For this concatenation to make sense, each column of T1 must be
compatible with the corresponding column of T2 - they must have compatible
types and, presumably, meanings. If this is not the case for the tables that
you wish to concatenate, for instance the columns are in different orders,
or the units differ between a column in T1 and its opposite number in T2,
you can use the icmd1 and/or icmd2 parameters to manipulate
the input tables so that the column sequences are compatible. See SUN/256
for some examples.
If the tables are similar to each other (same format, same
columns, same preprocessing stages required if any), you may find it easier
to use tcat instead.
OPTIONS¶
- nin=<count>
The number of input tables for this task. For each of the
input tables N there will be associated parameters
ifmtN,
inN
and
icmdN.
- ifmtN=<in-format>
Specifies the format of input table #N as specified by
parameter
inN. The known formats are listed in SUN/256. 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.
- inN=<tableN>
The location of input table #N. 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.
- icmdN=<cmds>
Specifies processing to be performed on input table #N as
specified by parameter
inN, before any other processing has taken
place. The value of this parameter is one or more of the filter commands
described in SUN/256. 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, and lines which are blank
or which start with a '#' character are ignored.
- ocmd=<cmds>
Specifies processing to be performed on the output table,
after all other processing has taken place. The value of this parameter is one
or more of the filter commands described in SUN/256. 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, and lines which are blank
or which start with a '#' character are ignored.
- omode=out|meta|stats|count|checksum|cgi|discard|topcat|samp|tosql|gui
The mode in which the result table will be output. The
default mode is
out, which means that the result will be written as a
new table to disk or elsewhere, as determined by the
out and
ofmt parameters. However, there are other possibilities, which
correspond to uses to which a table can be put other than outputting it, such
as displaying metadata, calculating statistics, or populating a table in an
SQL database. For some values of this parameter, additional parameters
(
<mode-args>) are required to determine the exact behaviour.
Possible values are
- out
- meta
- stats
- count
- checksum
- cgi
- discard
- topcat
- samp
- tosql
- gui
Use the
help=omode flag or see SUN/256 for more information.
- out=<out-table>
The location of the output table. This is usually a
filename to write to. If it is equal to the special value "-" (the
default) the output table will be written to standard output.
This parameter must only be given if omode has its default
value of "out".
- ofmt=<out-format>
Specifies the format in which the output table will be
written (one of the ones in SUN/256 - matching is case-insensitive and you can
use just the first few letters). If it has the special value
"
(auto)" (the default), then the output filename will be
examined to try to guess what sort of file is required usually by looking at
the extension. If it's not obvious from the filename what output format is
intended, an error will result.
This parameter must only be given if omode has its default
value of "out".
- seqcol=<colname>
Name of a column to be added to the output table which
will contain the sequence number of the input table from which each row
originated. This column will contain 1 for the rows from the first
concatenated table, 2 for the second, and so on.
- loccol=<colname>
Name of a column to be added to the output table which
will contain the location (as specified in the input parameter(s)) of the
input table from which each row originated.
- uloccol=<colname>
Name of a column to be added to the output table which
will contain the unique part of the location (as specified in the input
parameter(s)) of the input table from which each row originated. If not null,
parameters will also be added to the output table giving the pre- and post-fix
string common to all the locations. For example, if the input tables are
"/data/cat_a1.fits" and "/data/cat_b2.fits" then the
output table will contain a new column <colname> which takes the value
"a1" for rows from the first table and "b2" for rows from
the second, and new parameters "<colname>_prefix" and
"<colname>_postfix" with the values "/data/cat_" and
".fits" respectively.
- countrows=true|false
Whether to count the rows in the table before starting
the output. This is essentially a tuning parameter - if writing to an output
format which requires the number of rows up front (such as normal FITS) it may
result in skipping the number of passes through the input files required for
processing. Unless you have a good understanding of the internals of the
software, your best bet for working out whether to set this true or false is
to try it both ways
