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astro/
mean_by_radaz.pro
top source mean_by_radaz
Astro
result = mean_by_radaz(image, rbin=rbin, ntheta=ntheta, center=center, cropcircle=cropcircle, rotation=rotation, nan=nan)
Calculates the mean value of an image in bins of both radius and pie slices of azimuthal angle.
Return value
This function returns a structure containing the inner radii of each radial bin (tagged 'RADIAL_AXIS'), the image mean within each radial bin (tagged 'RADIAL_MEAN'), the starting azimuth of each azimuthal bin (tagged 'AZIMUTHAL_AXIS'), and the image mean within each azimuthal pie slice (tagged 'AZIMUTHAL_MEAN'). Note that azimuthal angle is calculated counterclockwise starting at the x-axis (unless ROTATION is specified).
Parameters
- image in
2D image array.
Keywords
- rbin in
Size of radial bins (in pixels). Default: 1.
- ntheta in
Number of azimuthal bins. Default: 8.
- center in
Pixel co-ordinate to consider the center. May be non-integer, or even off the image (as long as /CROPCIRCLE is not set). Default: Image center.
- cropcircle in
Set this keyword to crop out the corners of the image, i.e. use only those pixels within the largest circle that is fully enclosed in the image.
- rotation in
Start the first azimuthal bin at an angle ROTATION (in radians) from the x-axis. Default: 0.
- nan in
Set this keyword to check for NaN or Infinity when calculating the means. Any such elements are treated as missing data.
Examples
Calculate the radial and azimuthal means of some image data, cutting
out the "corners" that aren't fully sampled to the same radii. Use
radial bins 2 pixels wide and azimuthal bins 30 degrees wide.
imagedata = dist(25,25)
imagemeans = MEAN_BY_RADAZ(imagedata, RBIN=2, NTHETA=12, /CROPCIRCLE)
Author information
- History:
Written by: Jeremy Bailin, in response to a question by Andy Bohn. 17 June 2008 Public release in JBIU 18 June 2008 Fixed typo in documentation
File attributes
| Modification date: | Wed Apr 15 16:07:44 2009 |
| Lines: | 110 |