txdump: Select fields from the center task output text file

Package: irred

Usage

txdump textfiles fields expr

Parameters

textfiles: The APPHOT/DAOPHOT text database whose fields from selected records are to be printed.

fields: A template defining the fields to be printed from each selected record. The fields are specified by keywords defined in the text database output files #K and #N entries. Upper or lower case and minimum match abbreviations are permissible. Some fields such as "mag" may have multiple entries. An individual entry can be referenced by specifying an array index, e.g. "mag[2]" or several values can be selected by specifying a range of elements, e.g. "mag[1-3]". The fields are output in the order in which they are specified in the template.

expr: The boolean expression to be evaluated once per record. Only the fields in those records for which the boolean expression evaluates to yes are printed. If expr = "yes", the specified fields in all the records are printed.

headers = no: Preserve the APPHOT/DAOPHOT text database output format. The selected fields are printed on the standard output, preceded by parameters list, if parameters = yes, and the keyword, units, and format information, exactly as they appear in the text database.

parameters = yes: Print the keyword parameters records in APPHOT/DAOPHOT format on the standard output if headers = yes.

Description

TXDUMP selects a subset of fields specified by the fields parameter from an APPHOT/DAOPHOT text database or a list of databases by evaluating a boolean expression supplied by the user and prints the results on the standard output. If headers = no, the resultant output is in simple list format with all the specified fields in one line of text and adjacent fields separated by whitespace. The fields are printed in the order in which they appear in expr. If headers = yes, the selected fields are printed on the standard output, preceded by the parameter list, if parameters = yes, and the keyword, units, and format information, exactly as they appear in the text database. Newlines will not be inserted in the output so users should take care not to exceed the IRAF text file line limit of 161 characters.

The output records are selected on the basis of an input boolean expression expr whose variables are the field names specified by the #N keywords or the parameters specified by the #K keywords in the APPHOT/DAOPHOT text database. If after substituting the values associated with a particular record into the field name variables the expression evaluates to yes, that record is included in the output table.

The supported operators and functions are briefly described below. A detailed description of the boolean expression evaluator and its syntax can be found in the manual page for the IMAGES package HEDIT task.

The following logical operators can be used in the boolean expression.

equal             ==    not equal               !=
less than         <     less than or equal      <=
greater than      >     greater than or equal   >=
or                ||    and                     &&
negation          !     pattern match           ?=
concatenation     //

The pattern match character ?= takes a string expression as its first argument and a pattern as its second argument. The result is yes if the pattern is contained in the string expression. Patterns are strings which may contain pattern matching meta-characters. The meta-characters themselves can be matched by preceeding them with the escape character. The meta-characters listed below.

beginning of string     ^       end of string           $
one character           ?       zero or more characters *
white space             #       escape character        \
ignore case             {       end ignore case         }
begin character class   [       end character class     ]
not, in char class      ^       range, in char class    -

The expression may also include arithmetic operators and functions. The following arithmetic operators and functions are supported.

addition                +               subtraction             -
multiplication          *               division                /
negation                -               exponentiation          **
absolute value          abs(x)          cosine                  cos(x)
sine                    sin(x)          tangent                 tan(x)
arc cosine              acos(x)         arc sine                asin(x)
arc tangent             atan(x)         arc tangent             atan2(x,y)
exponential             exp(x)          square root             sqrt(x)
natural log             log(x)          common log              log10(x)
minimum                 min(x,y)        maximum                 max(x,y)
convert to integer      int(x)          convert to real         real(x)
nearest integer         nint(x)         modulo                  mod(x)

Examples

1. Print the fields XCENTER and YCENTER from the output of the APPHOT CENTER task.

pt> txdump image.ctr.1 XCENTER,YCENTER yes

2. Select the fields ID, XCENTER, YCENTER and the first three magnitudes MAG{1-3] from the output of the APPHOT PHOT task.

pt> txdump image.mag.2 "ID,XCEN,YCEN,MAG[1-3]" yes

3. Print all fields for all records in the above file with a magnitude through the first aperture of less than 20.0.

pt> txdump image.mag.2 * "MAG[1] < 20.0"

4. Print the id and all magnitudes for which magnitudes 1 and 2 are < 20.0 from a file which is the output of the APPHOT PHOT task.

pt> txdump image.mag.3 ID,MAG "MAG[1] < 20.0 && MAG[2] < 20.0"

5. Select the ID, XCENTER, YCENTER, MSKY and MAG fields from the output of the DAOPHOT NSTAR task for records where the magnitude is not INDEF, while preserving the format of the text database so it is suitable for input into a rerun of NSTAR.

pt> txdump image.nst.1 "ID,XCENTER,YCENTER,MSKY,MAG"  \
    "MAG[1] != INDEF" headers+

Bugs

TXDUMP does not allow arrays in the expression field.

Users should not dump more fields than fill a 161 character textline as IRAF does not currently fully support longer text lines.