Provided by: stilts_3.1.5-1_all bug

NAME

       stilts-tmatch1 - Performs a crossmatch internal to a single table

SYNOPSIS

       stilts tmatch1 [matcher=<matcher-name>] [params=<match-params>] [tuning=<tuning-params>]
                      [values=<expr-list>] [action=identify|keep0|keep1|wide2|wideN]
                      [progress=none|log|profile] [ifmt=<in-format>] [istream=true|false]
                      [in=<table>] [icmd=<cmds>] [ocmd=<cmds>]
                      [omode=out|meta|stats|count|cgi|discard|topcat|samp|tosql|gui] [out=<out-
                      table>] [ofmt=<out-format>]

DESCRIPTION

       tmatch1 performs efficient and flexible crossmatching between the rows of a single  table.
       It  can  match  rows  on the basis of their relative position in the sky, or alternatively
       using many other criteria such as separation in in some isotropic or anisotropic Cartesian
       space,  identity  of  a  key  value, or some combination of these; the full range of match
       criteria is dicussed in SUN/256.

       The basic task performed by the intra-table matcher is to identify groups of  rows  within
       the  table  which  match  each  other.  See  SUN/256  for  an  explanation of exactly what
       consitutes a match group. The result of identifying these groups is expressed as an output
       table  in  one  of  a  variety  of  ways, specified by the action parameter. These options
       include marking group membership in added columns and eliminating some or all  rows  which
       form part of a match group.

OPTIONS

       matcher=<matcher-name>
              Defines  the  nature  of the matching that will be performed. Depending on the name
              supplied, this may be positional matching using celestial or Cartesian coordinates,
              exact  matching  on  the  value  of  a  string  column, or other things. A list and
              explanation of the available matching algorithms is given  in  SUN/256.  The  value
              supplied  for  this parameter determines the meanings of the values required by the
              params, values* and tuning parameter(s).

       params=<match-params>
              Determines the parameters of this match. This is typically one or  more  tolerances
              such  as  error  radii.  It  may  contain  zero or more values; the values that are
              required depend on the match type selected by the matcher parameter. If it contains
              multiple values, they must be separated by spaces; values which contain a space can
              be 'quoted' or "quoted".

       tuning=<tuning-params>
              Tuning values for the matching process, if appropriate. It may contain zero or more
              values;  the  values  that  are  permitted depend on the match type selected by the
              matcher parameter. If it contains  multiple  values,  they  must  be  separated  by
              spaces;  values which contain a space can be 'quoted' or "quoted". If this optional
              parameter is not supplied, sensible defaults will be chosen.

       values=<expr-list>
              Defines the values from the input table which are used to determine whether a match
              has  occurred.  These  will  typically  be coordinate values such as RA and Dec and
              perhaps some per-row error values as well, though exactly what values are  required
              is  determined by the kind of match as determined by matcher. Depending on the kind
              of match, the number and type of the values required will  be  different.  Multiple
              values  should  be  separated  by  whitespace; if whitespace occurs within a single
              value it must be 'quoted' or "quoted". Elements of the expression list are commonly
              just  column  names,  but may be algebraic expressions calculated from zero or more
              columns as explained in SUN/256.

       action=identify|keep0|keep1|wide2|wideN
              Determines the form of the table which will be output as a result of  the  internal
              match.

                * identify:  The  output  table  is  the  same  as the input table except that it
                  contains two additional columns, GroupID and  GroupSize,  following  the  input
                  columns.  Each  group  of  rows  which  matched  is  assigned a unique integer,
                  recorded in the GroupID column, and the size of each group is recorded  in  the
                  GroupSize  column. Rows which don't match any others (singles) have null values
                  in both these columns.

                * keep0: The result is a new table containing only "single" rows,  that  is  ones
                  which don't match any other rows in the table. Any other rows are thrown out.

                * keep1:  The result is a new table in which only one row (the first in the input
                  table order) from each group of matching ones is retained. A subsequent  intra-
                  table match with the same criteria would therefore show no matches.

                * wideN: The result is a new "wide" table consisting of matched rows in the input
                  table stacked next to each other. Only groups of exactly N rows  in  the  input
                  table  are used to form the output table; each row of the output table consists
                  of the columns of the first group member, followed by the columns of the second
                  group  member and so on. The output table therefore has N times as many columns
                  as the input table. The column names in the new table have _1, _2, ... appended
                  to them to avoid duplication.

       progress=none|log|profile
              Determines  whether  information  on  progress of the match should be output to the
              standard error stream as it progresses.  For  lengthy  matches  this  is  a  useful
              reassurance  and  can give guidance about how much longer it will take. It can also
              be useful as a performance diagnostic.

              The options are:

                * none: no progress is shown

                * log: progress information is shown

                * profile: progress information and limited time/memory profiling information are
                  shown

       ifmt=<in-format>
              Specifies  the  format  of  the input table as specified by parameter in. 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.

       istream=true|false
              If set true, the input table specified by the  in  parameter  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 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).

       in=<table>
              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 ifmt parameter. Note that not all formats
                  can be streamed in this way.

                * 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.

       icmd=<cmds>
              Specifies processing to be performed on the input table as specified  by  parameter
              in, 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|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

                * 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".

SEE ALSO

       stilts(1)

       If  the  package  stilts-doc  is installed, the full documentation SUN/256 is available in
       HTML format:
       file:///usr/share/doc/stilts-doc/sun256/index.html

VERSION

       STILTS version 3.1-5-debian

       This is the Debian version of Stilts, which lack the support  of  some  file  formats  and
       network protocols. For differences see
       file:///usr/share/doc/stilts/README.Debian

AUTHOR

       Mark Taylor (Bristol University)

                                             Mar 2017                           STILTS-TMATCH1(1)