region - generate TeraScan latitude and longitude variables defining polygons surrounding data meeting various criteria

SYNOPSIS

region  [ parameter=value ]  [ inputfile outputfile ]

Parameters are variable, criteria, number, limits.

DESCRIPTION

region finds data elements in input 2-D TeraScan datasets that meet given criteria, and generates TeraScan latitude, longitude output variables that sequentially specify all polygons which circumscribe areas of contiguous data meeting those criteria. Since typically several polygons must be described using only the latitude, longitude data arrays, sequential polygons therein are delimited with badvalues. Bad value pairs at the same offset location in both latitude and longitude arrays indicate a terminated polygon.

The following criteria are supported:

good       - good (non-missing) values
bad        - bad (missing) values

equal      - good values == N
neq        - good values != N

lt         - good values <  N
le         - good values <= N

gt         - good values >  N
ge         - good values >= N

[]         - good values inside [N1, N2]
()         - good values inside (N1, N2)

[)         - good values inside [N1, N2)
(]         - good values inside (N1, N2]

outside[]  - good values outside [N1, N2]
outside()  - good values outside (N1, N2)

outside[)  - good values outside [N1, N2)
outside(]  - good values outside (N1, N2]

[ means closed on the left; i.e., the left endpoint is included in the interval. ] means closed on the right; i.e., the right endpoint is included in the interval.

( means open on the left; i.e., the left endpoint is not included in the interval. ) means open on the right; i.e., the right endpoint is not included in the interval.

PARAMETERS

variable: Name of the single variable to process. Wildcards * and ? are allowed. There is no default.

criteria: One of the criteria listed above. The default is good.

number: Number to compare against when criteria is equal, neq, lt, le, gt, or ge. The default is 0.

limits: Pair of numbers defining the interval when criteria is [], (), [), (], outside[], outside(), outside[), or outside(]. There is no default interval.

EXAMPLES

The following example shows how to circumscribe the non-missing values:

% region variable=avhrr_ch3 criteria=good avhrrdata testdata

The following example shows how to circumscribe positive data values, not including missing data:

% region variable=mcsst criteria=gt number=0 sstdata testdata

% contents testdata
printout       : char(  3) ? [no]
Contents of File: testdata    Page 1

Dimension       Size            Coord           Scale      Offset
 latitude       13618            y                  1           0
 longitude      13618            x                  1           0

Attribute       Type            Units           Value
 history         byte

Variable        Type            Units
 latitude        float
 longitude       float

Variable        Dimension       Size
 latitude        latitude      13618
 longitude      longitude      13618

Variable            BadValue    ValidMin    ValidMax       Scale      Offset
 latitude        -3.4028e+38 -1.7977e+308 1.7977e+308           1           0
 longitude       -3.4028e+38 -1.7977e+308 1.7977e+308           1           0