10.8 Examples

Here are some examples for defining new columns; the expressions below could appear as the <expr> in a tpipe addcol or sortexpr command).

Average

   (first + second) * 0.5

Square root

   sqrt(variance)

Angle conversion

   radiansToDegrees(DEC_radians)
   degreesToRadians(RA_degrees)

Conversion from string to number

   parseInt($12)
   parseDouble(ident)

Conversion from number to string

   toString(index)

Conversion between numeric types

   toShort(obs_type)
   toDouble(range)

or

   (short) obs_type
   (double) range

Conversion from sexagesimal to degrees

   hmsToDegrees(RA1950)
   dmsToDegrees(decDeg,decMin,decSec)

Conversion from degrees to sexagesimal

   degreesToDms($3)
   degreesToHms(RA,2)

Outlier clipping

   min(1000, max(value, 0))

Converting a magic value to null

   jmag == 9999 ? NULL : jmag

Converting a null value to a magic one

   NULL_jmag ? 9999 : jmag

Taking the third scalar element from an array-valued column

   psfCounts[2]

Converting spectral type to numeric value (e.g. "L3.5" -> 23.5, "M7" -> 17)

   "MLT".indexOf(spType.charAt(0)) * 10 + parseDouble(substring(spType,1)) + 10

Note this uses a couple of Java String instance methods (Section 10.9.2) which are not explicitly documented in this section.

Within a numeric range

   RA > 100 && RA < 120 && Dec > 75 && Dec < 85

Within a circle

   $2*$2 + $3*$3 < 1
   skyDistanceDegrees(ra0,dec0,hmsToDegrees(RA),dmsToDegrees(DEC))<15./3600.

First 100 rows

   index <= 100

(though you could use tpipe cmd='head 100' instead)

Every tenth row

   index % 10 == 0

(though you could use tpipe cmd='every 10' instead)

String equality/matching

   equals(SECTOR, "ZZ9 Plural Z Alpha")
   equalsIgnoreCase(SECTOR, "zz9 plural z alpha")
   startsWith(SECTOR, "ZZ")
   contains(ph_qual, "U")

String regular expression matching

   matches(SECTOR, "[XYZ] Alpha")

Test for non-blank value

   ! NULL_ellipticity