4.5 Examples

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

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 radians

    hmsToRadians(RA1950)
    dmsToRadians(decDeg,decMin,decSec)

Conversion from radians to sexagesimal

    radiansToDms($3)
    radiansToHms(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]

Within a numeric range

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

Within a circle

    $2*$2 + $3*$3 < 1
    skyDistance(ra0,dec0,degreesToRadians(RA),degreesToRadians(DEC))<15*ARC_MINUTE

First 100 rows

    index <= 100

(though you could use tpipe -head 100 instead)

Every tenth row

    index % 10 == 0

(though you could use tpipe -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