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## 4.4.13 Data gap detection: The -g option

GMT has several mechanisms that can determine line segmentation. Typically, data segments are separated by multiple segment header records (see section 4.4.14 on -m below). However, if key data columns contain a NaN we may also use that information to break lines into multiple segments. This behavior is modified by the parameter NAN_RECORDS which by default is set to skip, meaning such records are considered bad and simply skipped. If you wish such records to indicate a segment boundary then set this parameter to pass. Finally, you may wish to indicate gaps based on the data values themselves. The -g option is used to detect gaps based on one or more criteria (use -g+ if all the criteria must be met; otherwise only one of the specified criteria needs to be met to signify a data gap). Gaps can be based on excessive jumps in the x- or y-coordinates (-gx or -gy), or on the distance between points (-gd). Append the gap distance and optionally a unit for actual distances. For geographic data the optional unit may be meter [Default], kilometer, miles, or nautical miles. For programs that maps data to map coordinates you can optionally specify these criteria to apply to the projected coordinates (by using upper-case -gX, -gY or-gD). In that case, choose from inch, centimeter, meter, or points. [Default unit is controlled by MEASURE_UNIT]. Note: For -gx or -gy with time data the unit is instead controlled by TIME_UNIT.

Next: 4.4.14 Multiple segment data: Up: 4.4 Standardized command line Previous: 4.4.12 Data type selection: Contents Index