import numpy as np from scipy import * from pylab import * #! CHAPTER3 Demonstrates distributions of wave characteristics #!============================================================= #! #! Chapter3 contains the commands used in Chapter3 in the tutorial. #! #! Some of the commands are edited for fast computation. #! #! Section 3.2 Estimation of wave characteristics from data #!---------------------------------------------------------- #! Example 1 #!~~~~~~~~~~ speed = 'fast' #speed = 'slow' import wafo.data as wd import wafo.misc as wm import wafo.objects as wo xx = wd.sea() xx[:,1] = wm.detrend(xx[:,1]) ts = wo.mat2timeseries(xx) Tcrcr, ix = ts.wave_periods(vh=0, pdef='c2c', wdef='tw', rate=8) Tc, ixc = ts.wave_periods(vh=0, pdef='u2d', wdef='tw', rate=8) #! Histogram of crestperiod compared to the kernel density estimate #!~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 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) plot(t,ftc.eval_grid(t), t, ftc.eval_grid_fast(t),'-.') wm.plot_histgrm(Tc,normed=True) title('Kernel Density Estimates') axis([0, 8, 0, 0.5]) show() #! Extreme waves - model check: the highest and steepest wave #!~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ clf() S, H = ts.wave_height_steepness(method=0) indS = S.argmax() indH = H.argmax() ts.plot_sp_wave([indH, indS],'k.') show() #! Does the highest wave contradict a transformed Gaussian model? #!---------------------------------------------------------------- # TODO: Fix this #clf #inds1 = (5965:5974)'; #! points to remove #Nsim = 10; #[y1, grec1, g2, test, tobs, mu1o, mu1oStd] = ... # reconstruct(xx,inds1,Nsim); #spwaveplot(y1,indA-10) #hold on #plot(xx(inds1,1),xx(inds1,2),'+') #lamb = 2.; #muLstd = tranproc(mu1o-lamb*mu1oStd,fliplr(grec1)); #muUstd = tranproc(mu1o+lamb*mu1oStd,fliplr(grec1)); #plot (y1(inds1,1), [muLstd muUstd],'b-') #axis([1482 1498 -1 3]), #wafostamp([],'(ER)') #disp('Block = 6'), #pause(pstate) # ##!#! Expected value (solid) compared to data removed #clf #plot(xx(inds1,1),xx(inds1,2),'+'), hold on #mu = tranproc(mu1o,fliplr(grec1)); #plot(y1(inds1,1), mu), hold off #disp('Block = 7'), pause(pstate) #! Crest height PDF #!------------------ #! Transform data so that kde works better clf() wave_data = ts.wave_parameters() Ac = wave_data['Ac'] L2 = 0.6; import pylab ws.probplot(Ac**L2, dist='norm', plot=pylab) show() #!#! #! fac = kde(Ac,{'L2',L2},linspace(0.01,3,200)); pdfplot(fac) wafostamp([],'(ER)') simpson(fac.x{1},fac.f) disp('Block = 8'), pause(pstate) #!#! Empirical crest height CDF clf Fac = flipud(cumtrapz(fac.x{1},flipud(fac.f))); Fac = [fac.x{1} 1-Fac]; Femp = plotedf(Ac,Fac); axis([0 2 0 1]) wafostamp([],'(ER)') disp('Block = 9'), pause(pstate) #!#! Empirical crest height CDF compared to a Transformed Rayleigh approximation facr = trraylpdf(fac.x{1},'Ac',grec1); Facr = cumtrapz(facr.x{1},facr.f); hold on plot(facr.x{1},Facr,'.') axis([1.25 2.25 0.95 1]) wafostamp([],'(ER)') disp('Block = 10'), pause(pstate) #!#! Joint pdf of crest period and crest amplitude clf kopt2 = kdeoptset('L2',0.5,'inc',256); Tc = Tcf+Tcb; fTcAc = kdebin([Tc Ac],kopt2); fTcAc.labx={'Tc [s]' 'Ac [m]'} pdfplot(fTcAc) hold on plot(Tc,Ac,'k.') hold off wafostamp([],'(ER)') disp('Block = 11'), pause(pstate) #!#! Example 4: Simple wave characteristics obtained from Jonswap spectrum clf S = jonswap([],[5 10]); [m, mt]= spec2mom(S,4,[],0); disp('Block = 12'), pause(pstate) clf spec2bw(S) [ch Sa2] = spec2char(S,[1 3]) disp('Block = 13'), pause(pstate) #!#! Section 3.3.2 Explicit form approximations of wave characteristic densities #!#! Longuett-Higgins model for Tc and Ac clf t = linspace(0,15,100); h = linspace(0,6,100); flh = lh83pdf(t,h,[m(1),m(2),m(3)]); disp('Block = 14'), pause(pstate) #!#! Transformed Longuett-Higgins model for Tc and Ac clf [sk, ku ]=spec2skew(S); sa = sqrt(m(1)); gh = hermitetr([],[sa sk ku 0]); flhg = lh83pdf(t,h,[m(1),m(2),m(3)],gh); disp('Block = 15'), pause(pstate) #!#! Cavanie model for Tc and Ac clf t = linspace(0,10,100); h = linspace(0,7,100); fcav = cav76pdf(t,h,[m(1) m(2) m(3) m(5)],[]); disp('Block = 16'), pause(pstate) #!#! Example 5 Transformed Rayleigh approximation of crest- vs trough- amplitude clf xx = load('sea.dat'); x = xx; x(:,2) = detrend(x(:,2)); SS = dat2spec2(x); [sk, ku, me, si ] = spec2skew(SS); gh = hermitetr([],[si sk ku me]); Hs = 4*si; r = (0:0.05:1.1*Hs)'; fac_h = trraylpdf(r,'Ac',gh); fat_h = trraylpdf(r,'At',gh); h = (0:0.05:1.7*Hs)'; facat_h = trraylpdf(h,'AcAt',gh); pdfplot(fac_h) hold on pdfplot(fat_h,'--') hold off wafostamp([],'(ER)') disp('Block = 17'), pause(pstate) #!#! clf TC = dat2tc(xx, me); tc = tp2mm(TC); Ac = tc(:,2); At = -tc(:,1); AcAt = Ac+At; disp('Block = 18'), pause(pstate) #!#! clf Fac_h = [fac_h.x{1} cumtrapz(fac_h.x{1},fac_h.f)]; subplot(3,1,1) Fac = plotedf(Ac,Fac_h); hold on plot(r,1-exp(-8*r.^2/Hs^2),'.') axis([1. 2. 0.9 1]) title('Ac CDF') Fat_h = [fat_h.x{1} cumtrapz(fat_h.x{1},fat_h.f)]; subplot(3,1,2) Fat = plotedf(At,Fat_h); hold on plot(r,1-exp(-8*r.^2/Hs^2),'.') axis([1. 2. 0.9 1]) title('At CDF') Facat_h = [facat_h.x{1} cumtrapz(facat_h.x{1},facat_h.f)]; subplot(3,1,3) Facat = plotedf(AcAt,Facat_h); hold on plot(r,1-exp(-2*r.^2/Hs^2),'.') axis([1.5 3.5 0.9 1]) title('At+Ac CDF') wafostamp([],'(ER)') disp('Block = 19'), pause(pstate) #!#! Section 3.4 Exact wave distributions in transformed Gaussian Sea #!#! Section 3.4.1 Density of crest period, crest length or encountered crest period clf S1 = torsethaugen([],[6 8],1); D1 = spreading(101,'cos',pi/2,[15],[],0); D12 = spreading(101,'cos',0,[15],S1.w,1); SD1 = mkdspec(S1,D1); SD12 = mkdspec(S1,D12); disp('Block = 20'), pause(pstate) #!#! Crest period clf tic f_tc = spec2tpdf(S1,[],'Tc',[0 11 56],[],4); toc pdfplot(f_tc) wafostamp([],'(ER)') simpson(f_tc.x{1},f_tc.f) disp('Block = 21'), pause(pstate) #!#! Crest length if strncmpi(speed,'slow',1) opt1 = rindoptset('speed',5,'method',3); opt2 = rindoptset('speed',5,'nit',2,'method',0); else #! fast opt1 = rindoptset('speed',7,'method',3); opt2 = rindoptset('speed',7,'nit',2,'method',0); end clf if strncmpi(speed,'slow',1) NITa = 5; else disp('NIT=5 may take time, running with NIT=3 in the following') NITa = 3; end #!f_Lc = spec2tpdf2(S1,[],'Lc',[0 200 81],opt1); #! Faster and more accurate f_Lc = spec2tpdf(S1,[],'Lc',[0 200 81],[],NITa); pdfplot(f_Lc,'-.') wafostamp([],'(ER)') disp('Block = 22'), pause(pstate) f_Lc_1 = spec2tpdf(S1,[],'Lc',[0 200 81],1.5,NITa); #!f_Lc_1 = spec2tpdf2(S1,[],'Lc',[0 200 81],1.5,opt1); hold on pdfplot(f_Lc_1) wafostamp([],'(ER)') disp('Block = 23'), pause(pstate) #!#! clf simpson(f_Lc.x{1},f_Lc.f) simpson(f_Lc_1.x{1},f_Lc_1.f) disp('Block = 24'), pause(pstate) #!#! clf tic f_Lc_d1 = spec2tpdf(rotspec(SD1,pi/2),[],'Lc',[0 300 121],[],NITa); f_Lc_d12 = spec2tpdf(SD12,[],'Lc',[0 200 81],[],NITa); #! f_Lc_d1 = spec2tpdf2(rotspec(SD1,pi/2),[],'Lc',[0 300 121],opt1); #! f_Lc_d12 = spec2tpdf2(SD12,[],'Lc',[0 200 81],opt1); toc pdfplot(f_Lc_d1,'-.'), hold on pdfplot(f_Lc_d12), hold off wafostamp([],'(ER)') disp('Block = 25'), pause(pstate) #!#! clf opt1 = rindoptset('speed',5,'method',3); SD1r = rotspec(SD1,pi/2); if strncmpi(speed,'slow',1) f_Lc_d1_5 = spec2tpdf(SD1r,[], 'Lc',[0 300 121],[],5); pdfplot(f_Lc_d1_5), hold on else #! fast disp('Run the following example only if you want a check on computing time') disp('Edit the command file and remove #!') end f_Lc_d1_3 = spec2tpdf(SD1r,[],'Lc',[0 300 121],[],3); f_Lc_d1_2 = spec2tpdf(SD1r,[],'Lc',[0 300 121],[],2); f_Lc_d1_0 = spec2tpdf(SD1r,[],'Lc',[0 300 121],[],0); #!f_Lc_d1_n4 = spec2tpdf2(SD1r,[],'Lc',[0 400 161],opt1); pdfplot(f_Lc_d1_3), hold on pdfplot(f_Lc_d1_2) pdfplot(f_Lc_d1_0) #!pdfplot(f_Lc_d1_n4) #!simpson(f_Lc_d1_n4.x{1},f_Lc_d1_n4.f) disp('Block = 26'), pause(pstate) #!#! Section 3.4.2 Density of wave period, wave length or encountered wave period #!#! Example 7: Crest period and high crest waves clf tic xx = load('sea.dat'); x = xx; x(:,2) = detrend(x(:,2)); SS = dat2spec(x); si = sqrt(spec2mom(SS,1)); SS.tr = dat2tr(x); Hs = 4*si method = 0; rate = 2; [S, H, Ac, At, Tcf, Tcb, z_ind, yn] = dat2steep(x,rate,method); Tc = Tcf+Tcb; t = linspace(0.01,8,200); ftc1 = kde(Tc,{'L2',0},t); pdfplot(ftc1) hold on #! f_t = spec2tpdf(SS,[],'Tc',[0 8 81],0,4); f_t = spec2tpdf(SS,[],'Tc',[0 8 81],0,2); simpson(f_t.x{1},f_t.f) pdfplot(f_t,'-.') hold off wafostamp([],'(ER)') toc disp('Block = 27'), pause(pstate) #!#! clf tic if strncmpi(speed,'slow',1) NIT = 4; else NIT = 2; end #! f_t2 = spec2tpdf(SS,[],'Tc',[0 8 81],[Hs/2],4); tic f_t2 = spec2tpdf(SS,[],'Tc',[0 8 81],Hs/2,NIT); toc Pemp = sum(Ac>Hs/2)/sum(Ac>0) simpson(f_t2.x{1},f_t2.f) index = find(Ac>Hs/2); ftc1 = kde(Tc(index),{'L2',0},t); ftc1.f = Pemp*ftc1.f; pdfplot(ftc1) hold on pdfplot(f_t2,'-.') hold off wafostamp([],'(ER)') toc disp('Block = 28'), pause(pstate) #!#! Example 8: Wave period for high crest waves #! clf tic f_tcc2 = spec2tccpdf(SS,[],'t>',[0 12 61],[Hs/2],[0],-1); toc simpson(f_tcc2.x{1},f_tcc2.f) f_tcc3 = spec2tccpdf(SS,[],'t>',[0 12 61],[Hs/2],[0],3,5); #! f_tcc3 = spec2tccpdf(SS,[],'t>',[0 12 61],[Hs/2],[0],1,5); simpson(f_tcc3.x{1},f_tcc3.f) pdfplot(f_tcc2,'-.') hold on pdfplot(f_tcc3) hold off toc disp('Block = 29'), pause(pstate) #!#! clf [TC tc_ind v_ind] = dat2tc(yn,[],'dw'); N = length(tc_ind); t_ind = tc_ind(1:2:N); c_ind = tc_ind(2:2:N); Pemp = sum(yn(t_ind,2)<-Hs/2 & yn(c_ind,2)>Hs/2)/length(t_ind) ind = find(yn(t_ind,2)<-Hs/2 & yn(c_ind,2)>Hs/2); spwaveplot(yn,ind(2:4)) wafostamp([],'(ER)') disp('Block = 30'), pause(pstate) #!#! clf Tcc = yn(v_ind(1+2*ind),1)-yn(v_ind(1+2*(ind-1)),1); t = linspace(0.01,14,200); ftcc1 = kde(Tcc,{'kernel' 'epan','L2',0},t); ftcc1.f = Pemp*ftcc1.f; pdfplot(ftcc1,'-.') wafostamp([],'(ER)') disp('Block = 31'), pause(pstate) tic f_tcc22_1 = spec2tccpdf(SS,[],'t>',[0 12 61],[Hs/2],[Hs/2],-1); toc simpson(f_tcc22_1.x{1},f_tcc22_1.f) hold on pdfplot(f_tcc22_1) hold off wafostamp([],'(ER)') disp('Block = 32'), pause(pstate) disp('The rest of this chapter deals with joint densities.') disp('Some calculations may take some time.') disp('You could experiment with other NIT.') #!return #!#! Section 3.4.3 Joint density of crest period and crest height #!#! Example 9. Some preliminary analysis of the data clf tic yy = load('gfaksr89.dat'); SS = dat2spec(yy); si = sqrt(spec2mom(SS,1)); SS.tr = dat2tr(yy); Hs = 4*si v = gaus2dat([0 0],SS.tr); v = v(2) toc disp('Block = 33'), pause(pstate) #!#! clf tic [TC, tc_ind, v_ind] = dat2tc(yy,v,'dw'); N = length(tc_ind); t_ind = tc_ind(1:2:N); c_ind = tc_ind(2:2:N); v_ind_d = v_ind(1:2:N+1); v_ind_u = v_ind(2:2:N+1); T_d = ecross(yy(:,1),yy(:,2),v_ind_d,v); T_u = ecross(yy(:,1),yy(:,2),v_ind_u,v); Tc = T_d(2:end)-T_u(1:end); Tt = T_u(1:end)-T_d(1:end-1); Tcf = yy(c_ind,1)-T_u; Ac = yy(c_ind,2)-v; At = v-yy(t_ind,2); toc disp('Block = 34'), pause(pstate) #!#! clf tic t = linspace(0.01,15,200); kopt3 = kdeoptset('hs',0.25,'L2',0); ftc1 = kde(Tc,kopt3,t); ftt1 = kde(Tt,kopt3,t); pdfplot(ftt1,'k') hold on pdfplot(ftc1,'k-.') f_tc4 = spec2tpdf(SS,[],'Tc',[0 12 81],0,4,5); f_tc2 = spec2tpdf(SS,[],'Tc',[0 12 81],0,2,5); f_tc = spec2tpdf(SS,[],'Tc',[0 12 81],0,-1); pdfplot(f_tc,'b') hold off legend('kde(Tt)','kde(Tc)','f_{tc}') wafostamp([],'(ER)') toc disp('Block = 35'), pause(pstate) #!#! Example 10: Joint characteristics of a half wave: #!#! position and height of a crest for a wave with given period clf tic ind = find(4.4Hs/2); plot(Tc(ind), Ac(ind),'.'); hold on pdfplot(flh_g,'k-.') pdfplot(f_tcac_s) toc wafostamp([],'(ER)') disp('Block = 39'), pause(pstate) #!#! clf #! f_tcac = spec2thpdf(SS,[],'TcAc',[0 12 81],[0:0.2:8],opt1); #! pdfplot(f_tcac) disp('Block = 40'), pause(pstate) #!#! Section 3.4.4 Joint density of crest and trough height #!#! Section 3.4.5 Min-to-max distributions � Markov method #!#! Example 11. (min-max problems with Gullfaks data) #!#! Joint density of maximum and the following minimum clf tic tp = dat2tp(yy); Mm = fliplr(tp2mm(tp)); fmm = kde(Mm); f_mM = spec2mmtpdf(SS,[],'mm',[],[-7 7 51],opt2); pdfplot(f_mM,'-.') hold on pdfplot(fmm,'k-') hold off wafostamp([],'(ER)') toc disp('Block = 41'), pause(pstate) #!#! The joint density of �still water separated� maxima and minima. clf tic ind = find(Mm(:,1)>v & Mm(:,2)