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README.md

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+# angdist
+
+[![DOI](https://zenodo.org/badge/DOI/.svg)](https://doi.org/)
+
+Plot the 2D histogram of Euler angles covered by a set of cryo-EM particles.
+
+A single-particle cryo-EM reconstruction comes from a set of particle images
+corresponding to projections of identical particles in different orientations.
+Knowing how many particles contributed to any given projection orientation is
+important to assess the quality of a dataset. This command-line tool generates a
+2D histogram of particle orientations from a `run_*_data.star` file from a
+RELION Class3D or Refine3D job.
+
+## FAQ
+
+**Q:** Doesn't RELION already do this?
+
+**A:** RELION-3.1 produces a histogram of Euler angles, but in 3D
+(`*_angdist.bild` files). This is very convenient to visually relate specific
+Euler angles to the corresponding orientation of the 3D reconstruction of the
+particle. This tool is complementary to RELION in that it produces a 2D
+histogram. A 2D histogram is easier to look at globally, making it easy to
+rapidly spot problems (missing orientations, strongly preferred orientations,
+etc.). This tool doesn't require an installation of RELION, allowing one to
+inspect files quickly from a different computer. This tool also lets you adjust
+the number of bins in the histogram, and save the histogram as an SVG file
+(which is useful for adjusting styling to make a pretty figure).
+
+**Q:** Doesn't cryoSPARC already do this?
+
+**A:** Yes, cryoSPARC already prints out this exact same histogram. This tool,
+however, doesn't require an installation of cryoSPARC, allowing one to inspect
+files quickly from a different computer. This tool also lets you adjust the
+number of bins in the histogram, and save the histogram as an SVG file (which is
+useful for adjusting styling to make a pretty figure). Finally, this tool uses a
+default color scale that is much more readable to color blind people than the
+one used by cryoSPARC.
+
+## Acknowledgments
+
+I would not have been able to put this tool together without the
+[`starfile`](https://github.com/alisterburt/starfile) library.
+
+## Installation
+
+```
+$ pip install angdist
+```
+
+## Usage
+
+```
+$ angdist --help
+Usage: angdist [OPTIONS] <run_data.star>
+
+  Plots a 2D histogram of Euler angles distribution from a run_data.star
+  file produced by RELION.
+
+Options:
+  -t, --title TEXT        Title of the histogram (default: no title).
+  -c, --colormap TEXT     A color map supported by matplotlib (default:
+                          "viridis").
+
+  -g, --gridsize INTEGER  Number of hexagonal bins along the x axis (default:
+                          50).
+
+  -o, --output TEXT       File name to save the histogram (optional: with no
+                          file name, simply display the histogram on screen
+                          without saving it; recommended file formats: .png,
+                          .pdf, .svg or any format supported by matplotlib).
+
+  -h, --help              Show this message and exit.
+
+```
+