hanning
hanning( QDataSet ds, int len ) → QDataSet
Apply Hanning (Hann) windows to the data to prepare for FFT.  The 
 data is reformed into a rank 2 dataset [N,len].  Hanning windows taper 
 the ends of the interval to remove noise caused by the discontinuity.
 This is deprecated, and windowFunction should be used.
Parameters
ds - a QDataSet
len - an int
Returns:
data[N,len] with the hanning window applied.
See Also:
windowFunction(org.das2.qds.ops.Ops.FFTFilterType, int) 
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hashcodes
hashcodes( QDataSet ds ) → QDataSet
return a rank 1 hashcodes of each record the dataset, with one hashcodes value for each record.  The 
 value of hashcodes should repeat if the record repeats.  For a rank 1 dataset, the values are returned.
 
 NOTE: This is under-implemented and should not be used
 without understanding the code.
Parameters
ds - dataset with rank greater than 0.
Returns:
rank 1 dataset.
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hilbert
hilbert( QDataSet ds ) → QDataSet
Perform the Hilbert function on the rank 1 dataset, similar to
 the hilbert function in IDL and Matlab.
Parameters
ds - rank 1 dataset of length n.
Returns:
ds[n,2], complex array
See Also:
hilbert(QDataSet) 
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hilbertSciPy
hilbertSciPy( QDataSet ds ) → QDataSet
Perform the Hilbert function on the rank 1 dataset, similar to
 the scipy.signal.hilbert function in SciPy.  The result is
 form differently than hilbert.
Parameters
ds - rank 1 dataset of length n.
Returns:
ds[n,2], complex array
See Also:
hilbert(QDataSet) 
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histogram
histogram( QDataSet ds, double min, double max, double binSize ) → QDataSet
returns a rank 1 dataset that is a histogram of the data.  Note there
 will also be in the properties:
   count, the total number of valid values.
   nonZeroMin, the smallest non-zero, positive number
Parameters
ds - rank N dataset
min - the min of the first bin.  If min=-1 and max=-1, then automatically set the min and max.
max - the max of the last bin.
binSize - the size of each bin.
Returns:
a rank 1 dataset with each bin's count.  DEPEND_0 indicates the bin locations.
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histogram
histogram( QDataSet ds, Datum min, Datum max, Datum binsize ) → QDataSet
returns a rank 1 dataset that is a histogram of the data.  Note there
 will also be in the properties:
   count, the total number of valid values.
   nonZeroMin, the smallest non-zero, positive number
Parameters
ds - rank N dataset
min - the center of the first bin.  If min=-1 and max=-1, then automatically set the min and max.
max - the center of the last bin.
binsize - the size of each bin.
Returns:
a rank 1 dataset with each bin's count.  DEPEND_0 indicates the bin locations.
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histogram
histogram( QDataSet ds, String min, String max, String binsize ) → QDataSet
returns rank 1 dataset that is a histogram of the data.  This will use
 the units of ds to interpret min, max, and binsize.
Parameters
ds - rank N dataset
min - the center of the first bin.  If min=-1 and max=-1, then automatically set the min and max.
max - the center of the last bin.
binsize - the size of each bin.
Returns:
a QDataSet
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histogram
histogram( QDataSet ds, int binCount ) → QDataSet
returns a histogram of the dataset, based on the extent and scaletype of the data.
Parameters
ds - a QDataSet
binCount - number of bins
Returns:
a QDataSet
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histogram2d
histogram2d( QDataSet x, QDataSet y, int[] bins, QDataSet xrange, QDataSet yrange ) → QDataSet
make a 2-D histogram of the data in x and y.  For example
x= randn(10000)+1
y= randn(10000)+4
zz= histogram2d( x,y, [30,30], dataset([0,8]), dataset([-2,6]) )
plot( zz )
 The result will be a rank 2 dataset with DEPEND_0 and DEPEND_1 indicating
 the bin locations.  If the xrange or yrange is dimensionless, then 
 use the units of x or y.
Parameters
x - the x values
y - the y values
bins - number of bins in x and y
xrange - a rank 1 2-element bounds dataset, so that Units can be specified.
yrange - a rank 1 2-element bounds dataset, so that Units can be specified.
Returns:
a rank 2 dataset
See Also:
histogram(QDataSet, double, double, double) 
org.das2.qds.util.Reduction#histogram2D(QDataSet, QDataSet, QDataSet) 
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