hanaml.FFT.Rd
hanaml.FFT is a R wrapper for SAP HANA PAL fast-Fourier-transform.
hanaml.FFT(
data,
key,
num.type = NULL,
inverse = NULL,
window = NULL,
window.start = NULL,
window.length = NULL,
alpha = NULL,
beta = NULL,
attenuation = NULL,
flattop.mode = NULL,
flattop.precision = NULL,
tukey.r = NULL
)
DataFrame
DataFrame containting the data.
character
Name of the ID column.
list of characters, optional
Specify the number types(i.e. real or imaginary) of columns in data
,
e.g. num.type <- list(real = "COL1", imag = "COL2"),
where "COL1" and "COL2" are assumed to be column names in data
.
If only one column is specified in num.type
, only that column
will be applied FFT.
If not provided, then data
must contain exactly 3 columns,
and the two non-ID columns will be treated as real, imaginary part of data
respectively.
logical, optional
If FALSE, forward FFT is applied; otherwise inverse FFT is applied.
Defaults to FALSE.
character, optional
Specifies the type of tapering window function.
"none"
"hamming"
"hann"
"hanning"
"bartlett"
"triangular"
"bartlett_hann"
"blackman"
"blackman_harris"
"blackman_nuttall"
"bohman"
"cauchy"
"cheb"
"chebwin"
"cosine"
"sine"
"flattop"
"gaussian"
"kaiser"
"lanczos"
"sinc"
"nuttall"
"parzen"
"poisson"
"poisson_hann"
"poisson_hanning"
"rectangle"
"riemann"
"riesz"
"tukey"
Valid only when the input sequence is pure real and inverse
is not TRUE.
Defaults to "none", i.e. no tapering window applied to the input time-series.
integer, optional
Specifies the starting point of tapering window.
Valid only when window
is specified.
Defaults to 0.
integer, optional
Specifies the length of tapering window.
Valid only when window
is specified.
Defaults to the length from window.start
to the end of input.
numeric, optional
Specifies the value of \(\alpha\) parameter for the following tapering window functions:
"blackman"
"cauchy"
"gaussian"
"poisson"
"poisson_hann"
"poisson_hanning"
Default value is tapering window dependent, specified as follows:
"blackman": 0.16
"cauchy": 3.0
"gaussian": 2.5
"poisson": 2.0
"poisson_hann": 2.0
"poisson_hanning": 2.0
numeric, optional
Specifies the value of \(\beta\)(shape) parameter for the Kaiser window.
Valid only when window
is "kaiser".
Defaults to 8.6.
numeric, optional
Specifies the sidelobe attenuation for Chebyshev window.
Valid only when window
takes the value of "cheb" or "chebwin".
Defaults to 50.
character, optional
Specifies the mode of flattop window, either "symmetric" or "periodic".
Valid only when window
is "flattop".
Defaults to "symmetric".
character, optional
Specifies the precision of flat top window, either "none" or "octave".
numeric, optional
Specifies the value of shape parameter of the Tukey window,
equivalent to the fraction of the window inside the cosine tapered region.
Defaults to 0.5.
DataFrame
ID: with same name and type as input data.
REAL: type DOUBLE, representing real part of the transformed sequence.
IMAG: type DOUBLE, representing imaginary part of the transformed sequence.
Input DataFrame data:
> data$Collect()
ID RE IM
1 1 2.0 9.0
2 2 3.0 -3.0
3 3 5.0 0.0
4 4 0.0 0.0
5 5 -2.0 -2.0
6 6 -9.0 -7.0
7 7 7.0 0.0
Call the function:
> result <- hanaml.FFT(data, key = "ID")
Output:
> result$Collect()
ID REAL IMAG
1 1 6.000000 -3.000000
2 2 16.273688 -0.900317
3 3 -5.393946 26.26511
4 4 -13.88322 18.514840
5 5 -4.233990 -2.947800
6 6 9.657319 3.189618
7 7 5.580151 21.87854