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MEAN_BY_RADAZ

MEAN_BY_RADAZ

Name


    MEAN_BY_RADAZ

Purpose


    Calculates the mean value of an image in bins of both radius and
    pie slices of azimuthal angle.

Category


    Astro

Calling Sequence


    Result = MEAN_BY_RADAZ(Image)

Inputs


    Image: 2D image array.

Keyword Parameters


    RBIN: Size of radial bins (in pixels). Default: 1.
    NTHETA: Number of azimuthal bins. Default: 8.
    CENTER: 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.
    ROTATION: Start the first azimuthal bin at an angle ROTATION
                (in radians) from the x-axis. Default: 0.
    CROPCIRCLE: 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.
    NAN: Set this keyword to check for NaN or Infinity when
                calculating the means. Any such elements are treated
                as missing data.

Outputs


    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).

Example


    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)

Modification 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



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