7.10 Examples

Here are some general examples. They could be used to define synthetic columns or (where numeric) to define values for one of the axes in a plot.

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 7.9) 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

Every tenth row

    index % 10 == 0

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")

Subset intersection

    _1 && _2

Subset union

    _1 || _2

Other subset combinations

    (in_cluster && has_photometry) || ! _6

Test for non-blank value

    ! NULL_ellipticity