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Added TimeSeries.wave_parameters

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master
per.andreas.brodtkorb 14 years ago
parent e2161e8696
commit 478846ee01
2 changed files with 226 additions and 178 deletions
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30
pywafo/src/wafo/doc/tutorial_scripts/chapter3.py
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@ -32,29 +32,19 @@ import wafo.kdetools as wk
clf()
print(Tc.mean())
print(Tc.max())
t = linspace(0.01,8,200);
ftc = wk.TKDE(Tc, L2=0, inc=128)
kopt = kdeoptset('L2',0);
tic
ftc1 = kde(Tc,kopt,t);
toc
pdfplot(ftc1), hold on
histgrm(Tc,[],[],1)
axis([0 8 0 0.5])
wafostamp([],'(ER)')
disp('Block = 2'), pause(pstate)
#!#!
tic
kopt.inc = 128;
ftc2 = kdebin(Tc,kopt);
toc
pdfplot(ftc2,'-.')
plot(t,ftc.eval_grid(t), t, ftc.eval_grid_fast(t),'-.')
wm.histgrm(Tc,scale=True)
title('Kernel Density Estimates')
hold off
disp('Block = 3'), pause(pstate)
#!#! Extreme waves - model check: the highest and steepest wave
clf
axis([0, 8, 0, 0.5])
show()
#! Extreme waves - model check: the highest and steepest wave
#!~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
clf()
method = 0;
rate = 8;
[S, H, Ac, At, Tcf, Tcb, z_ind, yn] = ...

374
pywafo/src/wafo/objects.py
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@ -16,7 +16,7 @@ from __future__ import division
from wafo.transform.core import TrData
from wafo.transform.models import TrHermite, TrOchi, TrLinear
from wafo.stats import edf
from wafo.misc import (nextpow2, findtp, findtc, findcross,
from wafo.misc import (nextpow2, findtp, findtc, findcross,
ecross, JITImport, DotDict, gravity)
from wafodata import WafoData
from wafo.interpolate import SmoothSpline
@ -722,7 +722,7 @@ class TimeSeries(WafoData):
'''
def __init__(self, *args, **kwds):
self.name_ = kwds.pop('name', 'WAFO TimeSeries Object')
self.sensortypes = kwds.pop('sensortypes',['n', ])
self.sensortypes = kwds.pop('sensortypes', ['n', ])
self.position = kwds.pop('position', [zeros(3), ])
super(TimeSeries, self).__init__(*args, **kwds)
@ -832,7 +832,7 @@ class TimeSeries(WafoData):
t = linspace(0, lag * dt, lag + 1)
#cumsum = np.cumsum
acf = _wafocov.CovData1D(R[lags], t)
acf.sigma = sqrt(r_[ 0, r0**2 , r0**2 + 2 * cumsum(R[1:] ** 2)] / Ncens)
acf.sigma = sqrt(r_[ 0, r0 ** 2 , r0 ** 2 + 2 * cumsum(R[1:] ** 2)] / Ncens)
acf.children = [WafoData(-2. * acf.sigma[lags], t), WafoData(2. * acf.sigma[lags], t)]
acf.plot_args_children = ['r:']
acf.norm = norm
@ -991,8 +991,8 @@ class TimeSeries(WafoData):
Be = None
if method == 'psd':
nfft = 2 ** nextpow2(L)
pad_to = rate*nfft # Interpolate the spectrum with rate
nfft = 2 ** nextpow2(L)
pad_to = rate * nfft # Interpolate the spectrum with rate
S, f = psd(yy, Fs=1. / dt, NFFT=nfft, detrend=detrend, window=window(nfft),
noverlap=noverlap, pad_to=pad_to, scale_by_freq=True)
fact = 2.0 * pi
@ -1004,8 +1004,8 @@ class TimeSeries(WafoData):
R.data[:L] = R.data[:L] * win[L - 1::]
R.data[L] = 0.0
R.data = R.data[:L+1]
R.args = R.args[:L+1]
R.data = R.data[:L + 1]
R.args = R.args[:L + 1]
#R.plot()
#R.show()
spec = R.tospecdata(rate=rate, nugget=nugget)
@ -1030,156 +1030,8 @@ class TimeSeries(WafoData):
# S.S = zeros(nf+1,m-1);
return spec
def wave_height_steepness(self, rate=1, method=1, g=None):
'''
Returns waveheights and steepnesses from data.
Parameters
----------
rate : scalar integer
interpolation rate. Interpolates with spline if greater than one.
method : scalar integer
0 max(Vcf, Vcb) and corresponding wave height Hd or Hu in H
1 crest front (rise) speed (Vcf) in S and wave height Hd in H. (default)
-1 crest back (fall) speed (Vcb) in S and waveheight Hu in H.
2 crest front steepness in S and the wave height Hd in H.
-2 crest back steepness in S and the wave height Hu in H.
3 total wave steepness in S and the wave height Hd in H
for zero-downcrossing waves.
-3 total wave steepness in S and the wave height Hu in H.
for zero-upcrossing waves.
Returns
-------
S, H = Steepness and the corresponding wave height according to method
The parameters are calculated as follows:
Crest front speed (velocity) = Vcf = Ac/Tcf
Crest back speed (velocity) = Vcb = Ac/Tcb
Crest front steepness = 2*pi*Ac./Td/Tcf/g
Crest back steepness = 2*pi*Ac./Tu/Tcb/g
Total wave steepness (zero-downcrossing wave) = 2*pi*Hd./Td.^2/g
Total wave steepness (zero-upcrossing wave) = 2*pi*Hu./Tu.^2/g
The definition of g, Ac,At, Tcf, etc. are given in gravity and
wafo.definitions.
Example
-------
>>> import wafo.data as wd
>>> import wafo.objects as wo
>>> x = wd.sea()
>>> ts = wo.mat2timeseries(x)
>>> for i in xrange(-3,4):
... S, H = ts.wave_height_steepness(method=i)
... print(S[:2],H[:2])
(array([ 0.01186982, 0.04852534]), array([ 0.69, 0.86]))
(array([ 0.02918363, 0.06385979]), array([ 0.69, 0.86]))
(array([ 0.27797411, 0.33585743]), array([ 0.69, 0.86]))
(array([ 0.60835634, 0.60930197]), array([ 0.42, 0.78]))
(array([ 0.60835634, 0.60930197]), array([ 0.42, 0.78]))
(array([ 0.10140867, 0.06141156]), array([ 0.42, 0.78]))
(array([ 0.01821413, 0.01236672]), array([ 0.42, 0.78]))
>>> import pylab as plt
>>> h = plt.plot(S,H,'.')
>>> h = plt.xlabel('S')
>>> h = plt.ylabel('Hd [m]')
See also
--------
wafo.definitions
'''
# Ac,At = crest and trough amplitude, respectively
# Tcf,
# Tcb = Crest front and crest (rear) back period, respectively
# z_ind = indices to the zero-crossings (d,u) of the defining
# trough to trough waves (tw). If M>1 then
# z_ind=[N1 z_ind1 N2 z_ind2 ...NM z_indM] where
# Ni = length(z_indi) and z_indi are the indices to
# the zero-crossings of xi, i=1,2...M.
#
# yn = interpolated signal
#
# xn = [ti x1 x2 ... xM], where
# ti = time and x1 x2 ... xM are M column vectors of
# sampled surface elevation.
#[S,H,z_ind2,AC1,AT1,TFRONT1,TREAR1]=deal([]); % Initialize to []
dT = self.sampling_period()
#[N M] = size(xx);
if g is None:
g = gravity() #% acceleration of gravity
if rate>1:
dT = dT/rate
t0, tn = self.args[0], self.args[-1]
n = len(self.args)
ti = linspace(t0, tn, int(rate*n))
xi = interp1d(self.args , self.data.ravel(), kind='cubic')(ti)
else:
ti, xi = self.args, self.data.ravel()
#for ix=2:M
tc_ind, z_ind = findtc(xi,v=0,kind='tw')
tc_a = xi[tc_ind]
tc_t = ti[tc_ind]
AC = tc_a[1::2] # crest amplitude
AT= -tc_a[0::2] # trough amplitude
if (0<= method and method <=2):
# time between zero-upcrossing and crest [s]
tu = ecross(ti, xi, z_ind[1:-1:2],v=0)
TFRONT = tc_t[1::2]-tu
TFRONT[(TFRONT==0)]=dT # avoiding division by zero
if (0 >= method and method>=-2):
# time between crest and zero-downcrossing [s]
td = ecross(ti,xi, z_ind[2::2],v=0)
TREAR = td-tc_t[1::2]
TREAR[(TREAR==0)]=dT; #% avoiding division by zero
if method==0:
# max(Vcf, Vcr) and the corresponding wave height Hd or Hu in H
HU = AC+AT[1:]
HD = AC+AT[:-1]
T = np.where(TFRONT<TREAR, TFRONT, TREAR)
S = AC/T
H = np.where(TFRONT<TREAR, HD, HU)
elif method==1: # extracting crest front velocity [m/s] and
# Zero-downcrossing wave height [m]
H = AC+AT[:-1] # Hd
S = AC/TFRONT
elif method== -1: # extracting crest rear velocity [m/s] and
# Zero-upcrossing wave height [m]
H = AC+AT[1:] #Hu
S = AC/TREAR
elif method== 2: #crest front steepness in S and the wave height Hd in H.
H = AC + AT[:-1] #Hd
T = diff(ecross(ti,xi, z_ind[::2],v=0))
S = 2*pi*AC/T/TFRONT/g
elif method== -2: # crest back steepness in S and the wave height Hu in H.
H = AC+AT[1:]
T = diff(ecross(ti,xi, z_ind[1::2],v=0))
S = 2*pi*AC/T/TREAR/g
elif method==3: # total steepness in S and the wave height Hd in H
# for zero-doewncrossing waves.
H = AC+AT[:-1]
T = diff(ecross(ti,xi , z_ind[::2],v=0))# Period zero-downcrossing waves
S = 2*pi*H/T**2/g
elif method== -3: # total steepness in S and the wave height Hu in H for
# zero-upcrossing waves.
H = AC+AT[1::]
T = diff(ecross(ti, xi, z_ind[1::2],v=0))# Period zero-upcrossing waves
S = 2*pi*H/T**2/g
return S, H
def _trdata_cdf(self, **options):
'''
@ -1481,7 +1333,212 @@ class TimeSeries(WafoData):
mean = self.data.mean()
sigma = self.data.std()
return TurningPoints(self.data[ind], t, mean=mean, sigma=sigma)
def wave_parameters(self, rate=1):
'''
Returns several wave parameters from data.
Parameters
----------
rate : scalar integer
interpolation rate. Interpolates with spline if greater than one.
Returns
-------
parameters : dict
wave parameters such as
Ac, At : Crest and trough amplitude, respectively
Tcf, Tcb : Crest front and crest (rear) back period, respectively
Hu, Hd : zero-up-crossing and zero-downcrossing wave height, respectively.
Tu, Td : zero-up-crossing and zero-downcrossing wave period, respectively.
The definition of g, Ac,At, Tcf, etc. are given in gravity and
wafo.definitions.
Example
-------
>>> import wafo.data as wd
>>> import wafo.objects as wo
>>> x = wd.sea()
>>> ts = wo.mat2timeseries(x)
>>> wp = ts.wave_parameters()
>>> for name in ['Ac', 'At', 'Hu', 'Hd', 'Tu', 'Td', 'Tcf', 'Tcb']:
... print('%s' % name, wp[name][:2])
('Ac', array([ 0.25950546, 0.34950546]))
('At', array([ 0.16049454, 0.43049454]))
('Hu', array([ 0.69, 0.86]))
('Hd', array([ 0.42, 0.78]))
('Tu', array([ 6.10295202, 3.36978685]))
('Td', array([ 3.84377468, 6.35707656]))
('Tcf', array([ 0.42656819, 0.57361617]))
('Tcb', array([ 0.93355982, 1.04063638]))
>>> import pylab as plt
>>> h = plt.plot(wp['Td'],wp['Hd'],'.')
>>> h = plt.xlabel('Td [s]')
>>> h = plt.ylabel('Hd [m]')
See also
--------
wafo.definitions
'''
dT = self.sampling_period()
if rate > 1:
dT = dT / rate
t0, tn = self.args[0], self.args[-1]
n = len(self.args)
ti = linspace(t0, tn, int(rate * n))
xi = interp1d(self.args , self.data.ravel(), kind='cubic')(ti)
else:
ti, xi = self.args, self.data.ravel()
tc_ind, z_ind = findtc(xi, v=0, kind='tw')
tc_a = xi[tc_ind]
tc_t = ti[tc_ind]
Ac = tc_a[1::2] # crest amplitude
At = -tc_a[0::2] # trough amplitude
Hu = Ac + At[1:]
Hd = Ac + At[:-1]
tu = ecross(ti, xi, z_ind[1::2], v=0)
Tu = diff(tu)# Period zero-upcrossing waves
td = ecross(ti, xi , z_ind[::2], v=0)
Td = diff(td)# Period zero-downcrossing waves
Tcf = tc_t[1::2] - tu[:-1]
Tcf[(Tcf == 0)] = dT # avoiding division by zero
Tcb = td[1:] - tc_t[1::2]
Tcb[(Tcb == 0)] = dT; #% avoiding division by zero
return dict(Ac=Ac, At=At, Hu=Hu, Hd=Hd, Tu=Tu, Td=Td, Tcf=Tcf, Tcb=Tcb)
def wave_height_steepness(self, method=1, rate=1, g=None):
'''
Returns waveheights and steepnesses from data.
Parameters
----------
rate : scalar integer
interpolation rate. Interpolates with spline if greater than one.
method : scalar integer
0 max(Vcf, Vcb) and corresponding wave height Hd or Hu in H
1 crest front (rise) speed (Vcf) in S and wave height Hd in H. (default)
-1 crest back (fall) speed (Vcb) in S and waveheight Hu in H.
2 crest front steepness in S and the wave height Hd in H.
-2 crest back steepness in S and the wave height Hu in H.
3 total wave steepness in S and the wave height Hd in H
for zero-downcrossing waves.
-3 total wave steepness in S and the wave height Hu in H.
for zero-upcrossing waves.
Returns
-------
S, H = Steepness and the corresponding wave height according to method
The parameters are calculated as follows:
Crest front speed (velocity) = Vcf = Ac/Tcf
Crest back speed (velocity) = Vcb = Ac/Tcb
Crest front steepness = 2*pi*Ac./Td/Tcf/g
Crest back steepness = 2*pi*Ac./Tu/Tcb/g
Total wave steepness (zero-downcrossing wave) = 2*pi*Hd./Td.^2/g
Total wave steepness (zero-upcrossing wave) = 2*pi*Hu./Tu.^2/g
The definition of g, Ac,At, Tcf, etc. are given in gravity and
wafo.definitions.
Example
-------
>>> import wafo.data as wd
>>> import wafo.objects as wo
>>> x = wd.sea()
>>> ts = wo.mat2timeseries(x)
>>> for i in xrange(-3,4):
... S, H = ts.wave_height_steepness(method=i)
... print(S[:2],H[:2])
(array([ 0.01186982, 0.04852534]), array([ 0.69, 0.86]))
(array([ 0.02918363, 0.06385979]), array([ 0.69, 0.86]))
(array([ 0.27797411, 0.33585743]), array([ 0.69, 0.86]))
(array([ 0.60835634, 0.60930197]), array([ 0.42, 0.78]))
(array([ 0.60835634, 0.60930197]), array([ 0.42, 0.78]))
(array([ 0.10140867, 0.06141156]), array([ 0.42, 0.78]))
(array([ 0.01821413, 0.01236672]), array([ 0.42, 0.78]))
>>> import pylab as plt
>>> h = plt.plot(S,H,'.')
>>> h = plt.xlabel('S')
>>> h = plt.ylabel('Hd [m]')
See also
--------
wafo.definitions
'''
dT = self.sampling_period()
if g is None:
g = gravity() #% acceleration of gravity
if rate > 1:
dT = dT / rate
t0, tn = self.args[0], self.args[-1]
n = len(self.args)
ti = linspace(t0, tn, int(rate * n))
xi = interp1d(self.args , self.data.ravel(), kind='cubic')(ti)
else:
ti, xi = self.args, self.data.ravel()
tc_ind, z_ind = findtc(xi, v=0, kind='tw')
tc_a = xi[tc_ind]
tc_t = ti[tc_ind]
Ac = tc_a[1::2] # crest amplitude
At = -tc_a[0::2] # trough amplitude
if (0 <= method and method <= 2):
# time between zero-upcrossing and crest [s]
tu = ecross(ti, xi, z_ind[1:-1:2], v=0)
Tcf = tc_t[1::2] - tu
Tcf[(Tcf == 0)] = dT # avoiding division by zero
if (0 >= method and method >= -2):
# time between crest and zero-downcrossing [s]
td = ecross(ti, xi, z_ind[2::2], v=0)
Tcb = td - tc_t[1::2]
Tcb[(Tcb == 0)] = dT; #% avoiding division by zero
if method == 0:
# max(Vcf, Vcr) and the corresponding wave height Hd or Hu in H
Hu = Ac + At[1:]
Hd = Ac + At[:-1]
T = np.where(Tcf < Tcb, Tcf, Tcb)
S = Ac / T
H = np.where(Tcf < Tcb, Hd, Hu)
elif method == 1: # extracting crest front velocity [m/s] and
# Zero-downcrossing wave height [m]
H = Ac + At[:-1] # Hd
S = Ac / Tcf
elif method == -1: # extracting crest rear velocity [m/s] and
# Zero-upcrossing wave height [m]
H = Ac + At[1:] #Hu
S = Ac / Tcb
elif method == 2: #crest front steepness in S and the wave height Hd in H.
H = Ac + At[:-1] #Hd
Td = diff(ecross(ti, xi, z_ind[::2], v=0))
S = 2 * pi * Ac / Td / Tcf / g
elif method == -2: # crest back steepness in S and the wave height Hu in H.
H = Ac + At[1:]
Tu = diff(ecross(ti, xi, z_ind[1::2], v=0))
S = 2 * pi * Ac / Tu / Tcb / g
elif method == 3: # total steepness in S and the wave height Hd in H
# for zero-doewncrossing waves.
H = Ac + At[:-1]
Td = diff(ecross(ti, xi , z_ind[::2], v=0))# Period zero-downcrossing waves
S = 2 * pi * H / Td ** 2 / g
elif method == -3: # total steepness in S and the wave height Hu in H for
# zero-upcrossing waves.
H = Ac + At[1:]
Tu = diff(ecross(ti, xi, z_ind[1::2], v=0))# Period zero-upcrossing waves
S = 2 * pi * H / Tu ** 2 / g
return S, H
def wave_periods(self, vh=None, pdef='d2d', wdef=None, index=None, rate=1):
"""
Return sequence of wave periods/lengths from data.
@ -1540,10 +1597,11 @@ class TimeSeries(WafoData):
Example:
--------
Histogram of crest2crest waveperiods
>>> import wafo
>>> import wafo.data as wd
>>> import wafo.objects as wo
>>> import pylab as plb
>>> x = wafo.data.sea()
>>> ts = wafo.objects.mat2timeseries(x[0:400,:])
>>> x = wd.sea()
>>> ts = wo.mat2timeseries(x[0:400,:])
>>> T, ix = ts.wave_periods(vh=0.0,pdef='c2c')
>>> h = plb.hist(T)

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