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ccdhist - histogram plotter and gaussian fit for image data
ccdhist plots a histogram and computes
the first 4 moments of points obtained from the data values of an image(5NEMO)
cube. It calculates the mean, dispersion, skewness and kurtosis. It then
plots the data in the form of a histogram, optionally with a ’best’ gaussian
fit and residuals. It can also plot a cumulative histogram of the data.
The median is also optionally computed, for which an alternate sorting
routine can be selected (if available).
Using the nsigma keyword, outliers
can be removed and statistics re-computed (a.k.a. sigma-clipping).
was derived from tabhist(1NEMO)
, which works on ASCII tables, and derived
much of it’s user interface from that program.
The following parameters
are recognized in any order if the keyword is also given:
Points that fall exactly on the boundary of a bin, are added to the
right side. Another way of saying is that a cell includes the left side,
but is open ended on the right side, i.e. [---). Note this behavior is exactly
opposite that of SM’s behavior, which was used to compare results.
file, in tabular format [no default].
- Minimum value along X-axis
to include [default: autoscaling on minimum of datapoints].
- Maximum value along X-axis to include [default: autoscaling on maximum
- If one number is given, it is the number of
(equal size) bins between min and max. If more than one number is given,
they are the bin edges (thus one more than the number of bins need to be
supplied). [default: 16].
- Maximum count value per bin plotted
along the Y-axis [default: autoscaling].
- Take log of Y-axis? This
option is really redundant, since tabmath(1NEMO)
can handle any transformation
- Label along the X-axis [default: value].
- Label along the Y-axis [default: N or log(N)].
- Random verbiage,
will be plotted along right top of plot for identification [default: none].
The left top will contain the filename infile.
- Table output? If false,
a plot using your current yapp(5NEMO)
device will be given. If true, a simple
ascii version of a histogram is shown. The default choice of bins=16 keeps
all the information on a simple 80*24 screen. [Default: f]
- If true,
plot output will contain a gaussian fit. The "best" gaussian fit is the
one that has the same mean, dispersion and integrated area as the data.
- If true, the residual (data - fit) will be plotted
as a dashed line. [Default: t].
- Plot a cumulative histogram instead.
If set, the keywords gauss, residual, and ylog are automatically re-set
to false. [Default: f].
- Integrate the cumulative histogram,
instead of number count. This option makes no sense when cumulative is not
selected. [Default: f].
- Compute median too? This can be timeconsuming
for large numbers of points. [Default: t].
- If used, use this as
blankval. Default: none.
- Dual pass over the data, subtracting the
mean. This can be important if the data have a large average value with
a small spread around the mean. Notice that in this mode the mean is subtracted
but never added to the min/max/mean/median etc. Default: f
points more than nsigma times the sigma from the mean. Also known as sigma-clipping.
After each point sigma and mean are recomputed. [Default: none]
8-feb-2011 V1.0: cloned off tabhist PJT
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