Source code for

select - Select data table subsets based on multiple spatial criteria.
import pandas as pd
from pygmt.clib import Session
from pygmt.helpers import (

__doctest_skip__ = ["select"]

[docs]@fmt_docstring @use_alias( A="area_thresh", D="resolution", G="gridmask", I="reverse", J="projection", N="mask", R="region", V="verbose", Z="z_subregion", b="binary", d="nodata", e="find", f="coltypes", g="gap", h="header", i="incols", o="outcols", s="skiprows", w="wrap", ) @kwargs_to_strings(M="sequence", R="sequence", i="sequence_comma", o="sequence_comma") def select(data=None, outfile=None, **kwargs): r""" Select data table subsets based on multiple spatial criteria. This is a filter that reads (x, y) or (longitude, latitude) positions from the first 2 columns of *data* and uses a combination of 1-7 criteria to pass or reject the records. Records can be selected based on whether or not they are: 1. inside a rectangular region (``region`` [and ``projection``]) 2. within *dist* km of any point in *pointfile* 3. within *dist* km of any line in *linefile* 4. inside one of the polygons in the *polygonfile* 5. inside geographical features (based on coastlines) 6. has z-values within a given range, or 7. inside bins of a grid mask whose nodes are non-zero The sense of the tests can be reversed for each of these 7 criteria by using the ``reverse`` parameter. Full option list at :gmt-docs:`gmtselect.html` {aliases} Parameters ---------- data : str or {table-like} Pass in either a file name to an ASCII data table, a 2-D {table-classes}. outfile : str The file name for the output ASCII file. {area_thresh} resolution : str *resolution*\ [**+f**]. Ignored unless ``mask`` is set. Selects the resolution of the coastline data set to use ((**f**)ull, (**h**)igh, (**i**)ntermediate, (**l**)ow, or (**c**)rude). The resolution drops off by ~80% between data sets. [Default is **l**]. Append (**+f**) to automatically select a lower resolution should the one requested not be available [Default is abort if not found]. Note that because the coastlines differ in details it is not guaranteed that a point will remain inside [or outside] when a different resolution is selected. gridmask : str Pass all locations that are inside the valid data area of the grid *gridmask*. Nodes that are outside are either NaN or zero. reverse : str [**cflrsz**]. Reverse the sense of the test for each of the criteria specified: - **c** select records NOT inside any point's circle of influence. - **f** select records NOT inside any of the polygons. - **g** will pass records inside the cells with z equal zero of the grid mask in ``gridmask``. - **l** select records NOT within the specified distance of any line. - **r** select records NOT inside the specified rectangular region. - **s** select records NOT considered inside as specified by ``mask`` (and ``area_thresh``, ``resolution``). - **z** select records NOT within the range specified by ``z_subregion``. {projection} mask : str or list Pass all records whose location is inside specified geographical features. Specify if records should be skipped (s) or kept (k) using 1 of 2 formats: - *wet/dry*. - *ocean/land/lake/island/pond*. [Default is s/k/s/k/s (i.e., s/k), which passes all points on dry land]. {region} {verbose} z_subregion : str or list *min*\ [/*max*]\ [**+a**]\ [**+c**\ *col*]\ [**+i**]. Pass all records whose 3rd column (*z*; *col* = 2) lies within the given range or is NaN (use ``skiprows`` to skip NaN records). If *max* is omitted then we test if *z* equals *min* instead. This means equality within 5 ULPs (unit of least precision; Input file must have at least three columns. To indicate no limit on *min* or *max*, specify a hyphen (-). If your 3rd column is absolute time then remember to supply ``coltypes="2T"``. To specify another column, append **+c**\ *col*, and to specify several tests pass a list of arguments as you have columns to test. **Note**: When more than one ``z_subregion`` argument is given then the ``reverse="z"`` cannot be used. In the case of multiple tests you may use these modifiers as well: **+a** passes any record that passes at least one of your *z* tests [Default is all tests must pass], and **+i** reverses the tests to pass record with *z* value NOT in the given range. Finally, if **+c** is not used then it is automatically incremented for each new ``z_subregion`` argument, starting with 2. {binary} {nodata} {find} {coltypes} {gap} {header} {incols} {outcols} {skiprows} {wrap} Returns ------- output : pandas.DataFrame or None Return type depends on whether the ``outfile`` parameter is set: - :class:`pandas.DataFrame` table if ``outfile`` is not set. - None if ``outfile`` is set (filtered output will be stored in file set by ``outfile``). Example ------- >>> import pygmt >>> # Load a table of ship observations of bathymetry off Baja California >>> ship_data = pygmt.datasets.load_sample_data(name="bathymetry") >>> # Only return the data points that lie within the region between >>> # longitudes 246 and 247 and latitudes 20 and 21 >>> out =, region=[246, 247, 20, 21]) """ with GMTTempFile(suffix=".csv") as tmpfile: with Session() as lib: # Choose how data will be passed into the module table_context = lib.virtualfile_from_data(check_kind="vector", data=data) with table_context as infile: if outfile is None: outfile = lib.call_module( module="select", args=build_arg_string(kwargs, infile=infile, outfile=outfile), ) # Read temporary csv output to a pandas table if outfile == # if user did not set outfile, return pd.DataFrame try: column_names = data.columns.to_list() result = pd.read_csv(, sep="\t", names=column_names) except AttributeError: # 'str' object has no attribute 'columns' result = pd.read_csv(, sep="\t", header=None, comment=">") elif outfile != # return None if outfile set, output in outfile result = None return result