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diff --git a/noao/digiphot/ptools/doc/pselect.hlp b/noao/digiphot/ptools/doc/pselect.hlp new file mode 100644 index 00000000..92d4f163 --- /dev/null +++ b/noao/digiphot/ptools/doc/pselect.hlp @@ -0,0 +1,130 @@ +.help pselect Aug91 noao.digiphot.ptools +.ih +NAME +pselect - select records from an APPHOT/DAOPHOT database +.ih +USAGE +pselect infiles outfiles expr +.ih +PARAMETERS +.ls infiles +The APPHOT/DAOPHOT databases containing the records from which the +selection is to be made. +.le +.ls outfiles +The output APPHOT/DAOPHOT databases containing the selected records. +.le +.ls expr +The boolean expression to be evaluated. The expression +is evaluated once for each record. If \fIexpr\fR = yes, +a copy is made of the input file. +.le + +.ih +DESCRIPTION +PSELECT selects a subset of the records +from an APPHOT/DAOPHOT database or a list of databases +and writes the new records out to another database or list of +databases. + +The output records are selected on the basis of an input boolean +expression \fIexpr\fR whose variables are in the case of text +databases the field names +specified by the #N keywords or the parameters specified by the +#K keywords and in the case of an STSDAS table database the +column names. +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 database. + +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. + +.nf + equal == not equal != + less than < less than or equal <= + greater than > greater than or equal >= + or || and && + negation ! pattern match ?= + concatenation // +.fi + +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 are listed below. + +.nf + 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 - +.fi + +The boolean expression may also include arithmetic operators and functions. +The following arithmetic operators and functions are supported. + +.nf +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) +.fi + +.ih +EXAMPLES + +1. Select the records from the output of the APPHOT CENTER task for +which 100. <= XCENTER <= 200. and 300. <= YCENTER <= 400. + +.nf + pt> pselect m92.ctr.3 m92out \ + "XCE >= 100. && XCE <= 200. && YCE >= 300. && YCE <= 400." +.fi + +2. Select the records from the output of the APPHOT PHOT task for which +the first magnitude is not equal to INDEF. In the case of the +an STSDAS table database it may be necessary to escape the +leading square bracket. + +.nf + pt> pselect n4147.mag.3 n4147out "MAG[1] != INDEF" + + or + + pt> pselect n4147.mag.3 n4147out "MAG\[1] != INDEF" +.fi + +3. Select the records from the output of the DAOPHOT ALLSTAR task +for which CHI <= 5.0 and MERR <= .10 magnitudes. + +.nf + pt> pselect m92b.al.2 m92out "CHI <= 5.0 && MERR <= 1.0" +.fi + +.ih +BUGS +Array valued fields in text databases are not allowed in the expression +field. + +.ih +SEE ALSO +images.hedit,ptools.tbselect,tables.tselect,ptools.txselect +.endhelp |