Wrap fitcircle - #1550
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seisman
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Aug 14, 2026
seisman
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Aug 14, 2026
Co-authored-by: Dongdong Tian <seisman.info@gmail.com>
Co-authored-by: Dongdong Tian <seisman.info@gmail.com>
Co-authored-by: Dongdong Tian <seisman.info@gmail.com>
Co-authored-by: Dongdong Tian <seisman.info@gmail.com>
Co-authored-by: Dongdong Tian <seisman.info@gmail.com>
seisman
reviewed
Aug 15, 2026
Co-authored-by: Dongdong Tian <seisman.info@gmail.com>
Co-authored-by: Dongdong Tian <seisman.info@gmail.com>
Co-authored-by: Dongdong Tian <seisman.info@gmail.com>
Co-authored-by: Dongdong Tian <seisman.info@gmail.com>
seisman
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Aug 21, 2026
Co-authored-by: Dongdong Tian <seisman.info@gmail.com>
seisman
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| Find mean position and great or small circle fit to points on sphere. | ||
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| This method takes (longitude, latitude) values and converts them to Cartesian | ||
| three-vectors on the unit sphere. Then two locations are found: the mean | ||
| of the input positions, and the pole to the great circle which best fits | ||
| the input positions. | ||
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| Setting ``norm`` to ``1`` (L1 norm) approximates the minimization of the | ||
| sum of absolute values of cosines of angular distances. This solution | ||
| finds the mean position as the Fisher average of the data, and the pole | ||
| position as the Fisher average of the cross-products between the mean | ||
| and the data. Averaging cross-products gives weight to points in | ||
| proportion to their distance from the mean, analogous to the "leverage" | ||
| of distant points in linear regression in the plane. | ||
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| Setting ``norm`` to ``2`` (L2 norm) approximates the minimization of the | ||
| sum of squares of cosines of angular distances. It creates a 3 by 3 | ||
| matrix of sums of squares of components of the data vectors. The | ||
| eigenvectors of this matrix give the mean and pole locations. This | ||
| method may be more subject to roundoff errors when there are thousands | ||
| of data. The pole is given by the eigenvector corresponding to the | ||
| smallest eigenvalue; it is the least-well represented factor in the data | ||
| and is not easily estimated by either method. | ||
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| When the data are closely grouped along a great circle both solutions | ||
| are similar. If the data have large dispersion, the pole to the great | ||
| circle will be less well determined than the mean. Compare both | ||
| solutions as a qualitative check by calling :func:`pygmt.fitcircle` | ||
| twice, once for each ``norm``. |
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seisman
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Sep 8, 2026
Co-authored-by: Dongdong Tian <seisman.info@gmail.com>
Co-authored-by: Dongdong Tian <seisman.info@gmail.com>
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This pull request wraps the module
fitcircle.Preview at https://pygmt-dev--1550.org.readthedocs.build/en/1550/api/generated/pygmt.fitcircle.html
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make formatandmake checkto make sure the code follows the style guide.doc/api/index.rst.Slash Commands
You can write slash commands (
/command) in the first line of a comment to performspecific operations. Supported slash commands are:
/format: automatically format and lint the code/test-gmt-dev: run full tests on the latest GMT development version