Source code for pygmt.src.project

project - Project data onto lines or great circles, or generate tracks.
import pandas as pd
from pygmt.clib import Session
from pygmt.exceptions import GMTInvalidInput
from pygmt.helpers import (

[docs]@fmt_docstring @use_alias( A="azimuth", C="center", E="endpoint", F="convention", G="generate", L="length", N="flat_earth", Q="unit", S="sort", T="pole", V="verbose", W="width", Z="ellipse", f="coltypes", ) @kwargs_to_strings(E="sequence", L="sequence", T="sequence", W="sequence", C="sequence") def project(data=None, x=None, y=None, z=None, outfile=None, **kwargs): r""" Project data onto lines or great circles, or generate tracks. Project reads arbitrary :math:`(x, y [, z])` data and returns any combination of :math:`(x, y, z, p, q, r, s)`, where :math:`(p, q)` are the coordinates in the projection, :math:`(r, s)` is the position in the :math:`(x, y)` coordinate system of the point on the profile (:math:`q = 0` path) closest to :math:`(x, y)`, and :math:`z` is all remaining columns in the input (beyond the required :math:`x` and :math:`y` columns). Alternatively, ``project`` may be used to generate :math:`(r, s, p)` triples at equal increments along a profile using the ``generate`` parameter. In this case, the value of ``data`` is ignored (you can use, e.g., ``data=None``). Projections are defined in any (but only) one of three ways: 1. By a ``center`` and an ``azimuth`` in degrees clockwise from North. 2. By a ``center`` and ``endpoint`` of the projection path. 3. By a ``center`` and a ``pole`` position. To spherically project data along a great circle path, an oblique coordinate system is created which has its equator along that path, and the zero meridian through the Center. Then the oblique longitude (:math:`p`) corresponds to the distance from the Center along the great circle, and the oblique latitude (:math:`q`) corresponds to the distance perpendicular to the great circle path. When moving in the increasing (:math:`p`) direction, (toward B or in the azimuth direction), the positive (:math:`q`) direction is to your left. If a Pole has been specified, then the positive (:math:`q`) direction is toward the pole. To specify an oblique projection, use the ``pole`` option to set the pole. Then the equator of the projection is already determined and the ``center`` option is used to locate the :math:`p = 0` meridian. The center *cx/cy* will be taken as a point through which the :math:`p = 0` meridian passes. If you do not care to choose a particular point, use the South pole (*cx* = 0, *cy* = -90). Data can be selectively windowed by using the ``length`` and ``width`` options. If ``width`` is used, the projection width is set to use only data with :math:`w_{{min}} < q < w_{{max}}`. If ``length`` is set, then the length is set to use only those data with :math:`l_{{min}} < p < l_{{max}}`. If the ``endpoint`` option has been used to define the projection, then ``length="w"`` may be used to window the length of the projection to exactly the span from O to B. Flat Earth (Cartesian) coordinate transformations can also be made. Set ``flat_earth=True`` and remember that azimuth is clockwise from North (the y axis), NOT the usual cartesian theta, which is counterclockwise from the x axis. azimuth = 90 - theta. No assumptions are made regarding the units for :math:`x, y, r, s, p, q, dist, l_{{min}}, l_{{max}}, w_{{min}}, w_{{max}}`. If -Q is selected, map units are assumed and :math:`x, y, r, s` must be in degrees and :math:`p, q, dist, l_{{min}}, l_{{max}}, w_{{min}}, w_{{max}}` will be in km. Calculations of specific great-circle and geodesic distances or for back-azimuths or azimuths are better done using :gmt-docs:`mapproject` as project is strictly spherical. {aliases} Parameters ---------- data : str or {table-like} Pass in (x, y, z) or (longitude, latitude, elevation) values by providing a file name to an ASCII data table, a 2D {table-classes}. center : str or list *cx*/*cy*. Set the origin of the projection, in Definition 1 or 2. If Definition 3 is used, then *cx/cy* are the coordinates of a point through which the oblique zero meridian (:math:`p = 0`) should pass. The *cx/cy* is not required to be 90 degrees from the pole. azimuth : float or str Define the azimuth of the projection (Definition 1). endpoint : str or list *bx*/*by*. Define the end point of the projection path (Definition 2). convention : str Specify the desired output using any combination of **xyzpqrs**, in any order [Default is **xypqrsz**]. Do not space between the letters. Use lower case. The output will be columns of values corresponding to your ``convention``. The **z** flag is special and refers to all numerical columns beyond the leading **x** and **y** in your input record. The **z** flag also includes any trailing text (which is placed at the end of the record regardless of the order of **z** in ``convention``). **Note**: If ``generate`` is True, then the output order is hardwired to be **rsp** and ``convention`` is not allowed. generate : str *dist* [/*colat*][**+c**\|\ **h**]. Create :math:`(r, s, p)` output data every *dist* units of :math:`p` (See `unit` option). Alternatively, append */colat* for a small circle instead [Default is a colatitude of 90, i.e., a great circle]. If setting a pole with ``pole`` and you want the small circle to go through *cx*/*cy*, append **+c** to compute the required colatitude. Use ``center`` and ``endpoint`` to generate a circle that goes through the center and end point. Note, in this case the center and end point cannot be farther apart than :math:`2|\mbox{{colat}}|`. Finally, if you append **+h** then we will report the position of the pole as part of the segment header [Default is no header]. Note: No input is read and the value of ``data``, ``x``, ``y``, and ``z`` is ignored if ``generate`` is used. length : str or list [**w**\|\ *l_min*/*l_max*]. Project only those data whose *p* coordinate is within :math:`l_{{min}} < p < l_{{max}}`. If ``endpoint`` has been set, then you may alternatively use **w** to stay within the distance from ``center`` to ``endpoint``. flat_earth : bool Make a Cartesian coordinate transformation in the plane. [Default is ``False``; plane created with spherical trigonometry.] unit : bool Set units for :math:`x, y, r, s` degrees and :math:`p, q, dist, l_{{min}}, l_{{max}}, w_{{min}}, {{w_max}}` to km. [Default is ``False``; all arguments use the same units] sort : bool Sort the output into increasing :math:`p` order. Useful when projecting random data into a sequential profile. pole : str or list *px*/*py*. Set the position of the rotation pole of the projection. (Definition 3). {V} width : str or list *w_min*/*w_max*. Project only those data whose :math:`q` coordinate is within :math:`w_{{min}} < q < w_{{max}}`. ellipse : str *major*/*minor*/*azimuth* [**+e**\|\ **n**]. Used in conjunction with ``center`` (sets its center) and ``generate`` (sets the distance increment) to create the coordinates of an ellipse with *major* and *minor* axes given in km (unless ``flat_earth`` is given for a Cartesian ellipse) and the *azimuth* of the major axis in degrees. Append **+e** to adjust the increment set via ``generate`` so that the the ellipse has equal distance increments [Default uses the given increment and closes the ellipse]. Instead, append **+n** to set a specific number of unique equidistant data via ``generate``. For degenerate ellipses you can just supply a single *diameter* instead. A geographic diameter may be specified in any desired unit other than km by appending the unit (e.g., 3d for degrees) [Default is km]; the increment is assumed to be in the same unit. **Note**: For the Cartesian ellipse (which requires ``flat_earth``), the *direction* is counter-clockwise from the horizontal instead of an *azimuth*. outfile : str The file name for the output ASCII file. {f} Returns ------- track: pandas.DataFrame or None Return type depends on whether the ``outfile`` parameter is set: - :class:`pandas.DataFrame` table with (x, y, ..., newcolname) if ``outfile`` is not set - None if ``outfile`` is set (output will be stored in file set by ``outfile``) """ if "C" not in kwargs: raise GMTInvalidInput("The `center` parameter must be specified.") if "G" not in kwargs and data is None: raise GMTInvalidInput( "The `data` parameter must be specified unless `generate` is used." ) if "G" in kwargs and "F" in kwargs: raise GMTInvalidInput( "The `convention` parameter is not allowed with `generate`." ) with GMTTempFile(suffix=".csv") as tmpfile: if outfile is None: # Output to tmpfile if outfile is not set outfile = with Session() as lib: if "G" not in kwargs: # Choose how data will be passed into the module table_context = lib.virtualfile_from_data( check_kind="vector", data=data, x=x, y=y, z=z, required_z=False ) # Run project on the temporary (csv) data table with table_context as infile: arg_str = " ".join( [infile, build_arg_string(kwargs), "->" + outfile] ) else: arg_str = " ".join([build_arg_string(kwargs), "->" + outfile]) lib.call_module(module="project", args=arg_str) # if user did not set outfile, return pd.DataFrame if outfile == if "G" in kwargs: column_names = list("rsp") result = pd.read_csv(, sep="\t", names=column_names) else: result = pd.read_csv(, sep="\t", header=None, comment=">") # return None if outfile set, output in outfile elif outfile != result = None return result