ifft
ifft( QDataSet ds ) → QDataSet
Performs an inverse FFT on the provided rank 2 dataset of complex numbers.
A rank 2 dataset of complex numbers is returned.
Parameters
ds - a rank 2 dataset.
Returns:
a rank 2 dataset of complex numbers.
See Also:
Ops#fft(QDataSet)
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ifft( QDataSet ds, QDataSet window, int stepFraction, ProgressMonitor mon ) → QDataSet
imax
imax( QDataSet ds ) → int
return the index of the maximum value. This is to avoid inefficient
code like "where(slice.eq( max(slice) ))[0]"
Parameters
ds - rank 1 dataset
Returns:
the index of the maximum value, or -1 if the data is all fill.
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imax( Object ds ) → int
imin
imin( QDataSet ds ) → int
return the index of the minimum value. This is to avoid inefficient
code like "where(slice.eq( min(slice) ))[0]"
Parameters
ds - rank 1 dataset
Returns:
the index of the maximum value, or -1 if the data is all fill.
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imin( Object ds ) → int
indgen
indgen( int len0 ) → QDataSet
returns rank 1 dataset with values [0,1,2,...]
This returns an immutable dataset, so that it can
be used in Jython like so: for i in indgen(200000). Note before
February 2018, this would return a mutable dataset, and now
this returns an IndexGenDataSet, which is immutable.
Parameters
len0 - an int
Returns:
a QDataSet
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indgen( int len0, int len1 ) → QDataSet
indgen( int len0, int len1, int len2 ) → QDataSet
intarr
intarr( int len0 ) → QDataSet
create a dataset filled with zeros, stored in 4-byte ints.
Parameters
len0 - the zeroth dimension length
Returns:
rank 1 dataset filled with zeros.
See Also:
zeros(int)
dblarr(int)
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intarr( int len0, int len1 ) → QDataSet
intarr( int len0, int len1, int len2 ) → QDataSet
interpolate
interpolate( QDataSet vv, QDataSet findex ) → QDataSet
interpolate values from rank 1 dataset vv using fractional indeces
in rank N findex. For example, findex=1.5 means interpolate
the 1st and 2nd indeces with equal weight, 1.1 means
90% of the first mixed with 10% of the second.
Only modest extrapolations where findex>=-0.5 and findex<=L-0.5 are allowed, where L is the number of points.
The findex parameter must be dimensionless, to ensure that the caller is not passing in physical data.
Note there is no check on CADENCE.
Note nothing is done with DEPEND_0, presumably because was already calculated and used for findex.
Here is an example use of this in Autoplot's Jython code:
xx= [1,2,3,4]
yy= [2,4,5,4]
xxx= linspace(0,5,100)
yyy= interpolate( yy, findex(xx,xxx) )
plot( xx, yy, symbolSize=20 )
plot( addPlotElement(0), xxx, yyy )
Parameters
vv - rank 1 dataset having length L that is the data to be interpolated.
findex - rank N dataset of fractional indeces. This must be dimensionless, between -0.5 and L-0.5 and is typically calculated by the findex command.
Returns:
the result.
See Also:
interpolateMod interpolateMod, for data like longitude where 259 deg is 2 degrees away from 1 deg interpolateMod, for data like longitude where 259 deg is 2 degrees away from 1 deg
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interpolate( Object vv, Object findex ) → QDataSet
interpolate( QDataSet vv, QDataSet findex0, QDataSet findex1 ) → QDataSet
interpolate( Object vv, Object findex0, Object findex1 ) → QDataSet
interpolate( QDataSet vv, QDataSet findex0, QDataSet findex1, QDataSet findex2 ) → QDataSet
interpolateGrid
interpolateGrid( QDataSet vv, QDataSet findex0, QDataSet findex1 ) → QDataSet
interpolate values from rank 2 dataset vv using fractional indeces
in rank N findex, using bilinear interpolation. Here the two rank1
indexes form a grid and the result is rank 2.
Parameters
vv - rank 2 dataset.
findex0 - rank 1 dataset of fractional indeces for the zeroth index.
findex1 - rank 1 dataset of fractional indeces for the first index.
Returns:
rank 2 dataset
See Also:
findex findex, the 1-D findex command findex, the 1-D findex command
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interpolateGrid( Object x, Object y, Object z ) → QDataSet
interpolateMod
interpolateMod( QDataSet vv, QDataSet mod, QDataSet findex ) → QDataSet
like interpolate, but the findex is recalculated when the two bracketed points are closer in the
modulo space than they would be in the linear space.
Parameters
vv - rank 1 dataset that is the data to be interpolated. (e.g. longitude from 0 to 360deg)
mod - rank 0 dataset that is the mod of the space (e.g. 360deg), or rank 1 where the range is specified (e.g. -180 to 180).
findex - rank N dataset of fractional indeces. This must be dimensionless and is typically calculated by the findex command.
Returns:
the result, a rank 1 dataset with one element for each findex.
See Also:
interpolate(QDataSet,QDataSet)
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irange
irange( double min, double max, int step ) → Iterator
mimic the Jython xrange function for use in loops. The returns
the integers in the sequence, like xrange, but avoids the confusing
"xrange" name and this also takes double
values so that it can be used in graphics routines which use double.
Parameters
min - the first value
max - the last value, plus one (exclusive).
step - the increment between elements.
Returns:
an iterator for the numbers in the interval.
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irange( double min, double max ) → Iterator
irange( double max ) → Iterator
isAngleRange
isAngleRange( QDataSet ds, boolean strict ) → Double
return true if the dataset can be interpreted as radian degrees from 0 to PI or from 0 to 2*PI.
Parameters
ds - any QDataSet.
strict - return null if it's not clear that the units are degrees.
Returns:
the multiplier to make the dataset into radians, or null.
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isBundle
isBundle( QDataSet zds ) → boolean
return true if the dataset is a bundle. It is rank 2 or rank 1, and
has the last dimension a bundle dimension.
Parameters
zds - the dataset
Returns:
true if the dataset is a bundle.
See Also:
org.das2.qds.examples.Schemes
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isLegacyBundle
isLegacyBundle( QDataSet zds ) → boolean
return true if DEPEND_1 is set and its units are EnumerationUnits. This
was the pre-bundle way of representing a bundle of datasets. It might
be supported indefinitely, because it has some nice rules about the data.
For example, bundled data must be of the same units since there is no place to put
the property, and each bundled item must be rank 1.
Parameters
zds - rank 1 or rank 2 dataset
Returns:
return true if DEPEND_1 is set and its units are EnumerationUnits.
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isSafeName
isSafeName( String name ) → boolean
returns true if the name is a Java-style identifier, starting
with one of a-z, A-Z, or _; followed by a-z, A-Z, 0-9, or _; and
note that only ASCII characters are allowed.
Parameters
name - a String
Returns:
true if the name is a safe identifier name.
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