pygmt.x2sys_init

pygmt.x2sys_init(tag, region=None, verbose=False, **kwargs)[source]

Initialize a new x2sys track database.

Serves as the starting point for x2sys and initializes a set of data bases that are particular to one kind of track data. These data, their associated data bases, and key parameters are given a short-hand notation called an x2sys TAG. The TAG keeps track of settings such as file format, whether the data are geographic or not, and the binning resolution for track indices.

Before you can run pygmt.x2sys_init you must set the environment variable X2SYS_HOME to a directory where you have write permission, which is where x2sys can keep track of your settings.

Full GMT docs at https://docs.generic-mapping-tools.org/6.6/supplements/x2sys/x2sys_init.html.

Aliases:

  • D = fmtfile

  • E = suffix

  • F = force

  • G = discontinuity

  • I = spacing

  • N = units

  • W = gap

  • j = distcalc

  • R = region

  • V = verbose

Parameters:

  • tag (str) – The unique name of this data type x2sys TAG.

  • fmtfile (str) –

    Format definition file prefix for this data set (see GMT’s Format Definition Files for more information). Specify full path if the file is not in the current directory.

    Some file formats already have definition files premade. These include:

    • mgd77 (for plain ASCII MGD77 data files)

    • mgd77+ (for enhanced MGD77+ netCDF files)

    • gmt (for old mgg supplement binary files)

    • xy (for plain ASCII x, y tables)

    • xyz (same, with one z-column)

    • geo (for plain ASCII longitude, latitude files)

    • geoz (same, with one z-column).

  • suffix (str) – Specify the file extension (suffix) for these data files. If not given we use the format definition file prefix as the suffix (see fmtfile).

  • discontinuity (str) – d|g. Select geographical coordinates. Append d for discontinuity at the Dateline (makes longitude go from -180° E to +180° E) or g for discontinuity at Greenwich (makes longitude go from 0° E to 360° E [Default]). If not given we assume the data are Cartesian.

  • spacing (str or list) – dx[/dy]. dx and optionally dy is the grid spacing. Append m to indicate minutes or s to indicate seconds for geographic data. These spacings refer to the binning used in the track bin-index data base.

  • units (str or list) –

    d|sunit. Set the units used for distance and speed when requested by other programs. Append d for distance or s for speed, then give the desired unit as:

    • c: Cartesian userdist or userdist/usertime

    • e: meters or m/s

    • f: feet or ft/s

    • k: kilometers or km/hr

    • m: miles or mi/hr

    • n: nautical miles or knots

    • u: survey feet or sft/s

    [Default is units=["dk", "se"] (km and m/s) if discontinuity is set, and units=["dc", "sc"] otherwise (e.g., for Cartesian units)].

  • region (str or list) – xmin/xmax/ymin/ymax[+r][+uunit]. Specify the region of interest.

  • verbose (bool or str) – Select verbosity level [Full usage].

  • gap (str or list) – t|dgap. Give t or d and append the corresponding maximum time gap (in user units; this is typically seconds [Default is infinity]), or distance (for units, see units) gap [Default is infinity]) allowed between the two data points immediately on either side of a crossover. If these limits are exceeded then a data gap is assumed and no COE will be determined.

  • distcalc (str) – Determine how spherical distances are calculated [Full usage].