Align time axes of two plots?

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Louise Wilson
Louise Wilson on 19 Oct 2020
Edited: Louise Wilson on 20 Oct 2020
I have two figures where the x-axis is time, and they overlap in time. One is a spectrogram of a sound file and the other shows the distance of a vessel from where the sound file was recorded. The x-axis overlap in time but I am wondering how I could sync them up accurately? I have adjusted the time axes so they line up in time but visually they are off slighty. I have tried removing the colourbar but that doesn't help, plus I would like to keep the colourbar in. Also, how could I plot two spectrograms (two .wav files) side by side?
%Input variables
site=3; %site working on
wavfolder=('Y:\SoundTrap\Boats\wav\Kawau\006_Kawau_5278'); %wav file folder
wavfile=('5278.191210100314.wav'); %file working on
hydrophonesites=('Y:\AIS data\CPA_FILT\hydro_locations.xlsx'); %hydrophone sites
gpsfolder=('Y:\HOLUX GPS data'); %gps folder
gpsfile=('20191210_GPS_Koura.csv'); %gps file
%Get hydrophone sites
PAMlocs = xlsread(hydrophonesites,'A2:B11');
[~,PAMlocname] = xlsread(hydrophonesites,'C2:C11');
[~,PAMloccode] = xlsread(hydrophonesites,'E2:E11');
disp(PAMlocname{site})
PAMlat = PAMlocs(site,1);
PAMlon = PAMlocs(site,2);
%Get GPS data
opts=detectImportOptions(fullfile(gpsfolder,gpsfile));
opts.SelectedVariableNames={'LOCALDATE','LOCALTIME','LAT','LONGITUDE'}; %only read variables of interest
opts=setvaropts(opts,'LOCALDATE','InputFormat','dd/MM/yyyy'); %read date in correct format
gps=readtable(fullfile(gpsfolder,gpsfile),opts); %read file
gps.LOCALDATE=gps.LOCALDATE+gps.LOCALTIME; %add time to datetime
gps.LOCALDATE.Format='dd-MM-yyyy HH:mm:ss';
gps.LOCALDATE=datenum(gps.LOCALDATE);
gps = removevars(gps, 'LOCALTIME');
gps.LOCALDATE=datenum(gps.LOCALDATE);
gps=table2array(gps);
%Calculate distances between boat and hydrophone
gps(:,4)=deg2km(distance(gps(:,2),gps(:,3),PAMlat,PAMlon));
%Plot spectrogram
subplot(2,1,2)
wavfilename=fullfile(wavfolder, wavfile);
%Input variables for audioread:
fs=144000;
tlo=1.0; %select only part of data and so remove cal.tone
thi=299.0;
nlo=fs*tlo; %multiply fs by tlo to get starting point
nup=fs*thi; %do the same for end point
dur=0.5;
nfft=window;
window=round(fs*dur);
overlap=window/2; %50% overlap
%Get calibration info:
SN=strsplit(wavfile, {'.','\'});
SN1=char(SN(1));
serialNo=str2num(SN1);
switch serialNo
case 5278
cal=175.9;
otherwise error('Unknown ST serial');
end
cal=power(10,cal/20); %calculate calibration value
[xbit,fs]=audioread(fullfile(wavfolder,wavfile), [nlo nup]); %read in wav
xbit=detrend(xbit); %remove DC offset
calxbit=xbit*cal; %apply calibration
[cal,F,T,P] = spectrogram(calxbit,window,overlap,nfft,fs,'yaxis'); %perform FFT and plot
h = pcolor(T,F,10*log10(P));
set(h,'EdgeColor','none');
subplot(2,1,2)
set(gca,'tickdir','out','layer','top','fontname',... %change size of axes
'arial','fontsize',12);
colormap(gca,parula); %change colour scheme of plot
%Y axis
ylabel('Frequency (Hz)','FontSize',18,'FontName','Arial'); %label
ylim([50 5000]); %sets the y -axis frequency limits
set(gca, 'YScale', 'log'); %set y-axis as lin or log
%X axis
xlabel('Time (seconds)','FontSize',18,'FontName','Arial'); %label
xlim([1,299]); %change range of x-axis
%xticks(2:20:299); %x axis labels in intervals of 15
%Colourbar
y=ylabel(colorbar,['PSD (dB re 1 uPa^2 Hz^-^1)'],'fontname','arial',...
'fontsize',18, 'Rotation', 270, 'Position',...
[4.32857152393886 82.8072636129137 0]); %add in PSD colour bar
caxis([40 120]); % sets scale on colour bar
%Get dates for x axis
fileparts=strsplit(wavfile,'.');
filetime=fileparts(2)
filetime=datetime(filetime,'InputFormat','yyMMddHHmmss')
starttime=filetime+seconds(tlo)
endtime=filetime+seconds(thi)
datevector=starttime:seconds(1):endtime; %times of .wav file in 1s interval
%find gps times which overlap with .wav file times
[matchingtimes,Locb]=ismember(datetime(gps(:,1),'ConvertFrom','datenum'),datevector);
gps_sub=gps(matchingtimes,:); %subset gps times
%find position of gps times in .wav file times
[Lia,Locb]=ismember(datevector,datetime(gps_sub(:,1),'ConvertFrom','datenum'));
datevector_sub=datevector(Lia); %subset wav file datetimes to match gps times
%where in datevector does first value of datevector_sub occur?
%[Lia,Locb]=ismember(datevector_sub,datevector);
%firstvalue=Locb(1)
%xticks(firstvalue:20:299);
%times=datevector(firstvalue):seconds(20):endtime;
%OR
xticks(1:20:299);
times=datevector(1):seconds(20):datevector(299);
xlabels=cellstr(datestr(times));
xticklabels(xlabels);
xtickangle(45);
%Plot GPS
hold on
subplot(2,1,2)
plot(datetime(gps_sub(:,1),'ConvertFrom','datenum'),gps_sub(:,4),'LineWidth',2,'Color',[1 0 0])
xticks(starttime:seconds(20):endtime); %change range of x-axis using times from .wav
xlim([starttime, endtime]);
xtickangle(45);
ylabel('Distance (km) of vessel to hydrophone');
%We want 'starttime' to be the first value in all plots, but 'firsttime' is
%the first labelled time.
%gps_sub_dt=datetime(gps_sub(:,1),'ConvertFrom','datenum');
timebefore=(firsttime-seconds(6)):seconds(1):firsttime-seconds(1);
check=ismember(datetime(gps(:,1),'ConvertFrom','datenum'),timebefore);
earliertime=gps(check,:);
gps_sub=[earliertime; gps_sub]; %extend start time of gps data to meet with .wav file contents
set(colorbar,'visible','off'); %align plots

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