B.44 tpipe: Performs pipeline processing on a table

tpipe performs all kinds of general purpose manipulations which take one table as input. It is extremely flexible, and can do the following things amongst others:

• calculate statistics
• display metadata
• select rows in various ways, including algebraically
• define new columns as algebraic functions of old ones
• delete or rearrange columns
• sort rows
• convert between table formats

The basic operation of tpipe is that it reads an input table, performs zero or more processing steps on it, and then does something with the output. There are therefore three classes of things you need to tell it when it runs:

Input table location

Specified by the in, ifmt and istream parameters.

Processing steps

Either provide a string giving steps as the value of one or more cmd parameters, or the name of a file containing the steps using the script parameter. The steps that you can perform are described in Section 6.1.

Output table destination

What happens to the output table is determined by the value of the omode parameter. By default, omode=out, in which case the table is written to a new table file in a format determined by ofmt. However, you can do other things with the result such as calculate the per-column statistics (omode=stats), view only the table and column metadata (omode=meta), display it directly in TOPCAT (omode=topcat) etc.

The parameters mentioned above are listed in detail in the next section.

• B.44.1 Usage
• B.44.2 Examples