convert hours to days on y-axis

Dear all,

I have a file a1, contains two columns, first one is number of segments (each segments represents 12 hours) for one years and seconds columns has data for that segment. I plot the data w.r.t hours.

Is it possible to convert scale from hours to day numbers or date?

here is the example of 6 day data, date started from 10 Oct 2018.

1	0
2	0
3	0
4	0.199999999999996
5	0
6	0
7	0
8	0.199999999999996
9	0
10	0
11	0
12	0

What i want to plot axis w.r.t date, here is the example

10/10/2018	0
        	0
11/10/2018	0
        	0.199999999999996
12/10/2018	0
        	0

Thanks in advance

Answer 1

[Chunru]

x = [
1	0
2	0
3	0
4	0.199999999999996
5	0
6	0
7	0
8	0.199999999999996
9	0
10	0
11	0
12	0];
bar(datetime('10/10/2018', 'InputFormat', 'dd/MM/yyyy') + hours(x(:,1)*12), x(:,2));
xtickformat('dd/MM/yyyy')

[AA]

Thanks for your responses:

Here is a bit modification:

how can we change if there are three set of data;

   %%here time is -100 to 100 with interval of 0.2 sec
   %day is the number of segments (12 hours)
   %z2 is respective data for each points

imagesc(time,day,z2) %here time is -100 to 100 with interval of 0.2 sec
    colormap(jet)
    xlim([-100 100]);
    NumTicks = 4;
    L = get(gca,'YLim');
    set(gca,'YTick',linspace(L(1),L(2),NumTicks));
    datetick('y','mmmdd','keeplimits','keepticks');
    ylabel('(Date)');

In this case, is it possible to convert the day (no of segments) to date?

[Chunru]

For imagesc, you cannot use datetime as axis variable. You need to change axis labels instead.

t = [-100:.2:100];
d = [0:10];
imagesc(t,d,rand(20,20));
%YTickStr = string(datetime('10/10/2018', 'InputFormat', 'dd/MM/yyyy', 'Format', 'dd/MM/yyyy') + hours(d*12));
YTickStr = char(datetime('10/10/2018', 'InputFormat', 'dd/MM/yyyy', 'Format', 'dd/MM/yyyy') + hours(d*12));

set(gca, 'XTick', -100:50:100, 'XTickLabel', char((-100:50:100)'*.2+"s"), ...
    'YTick', 0:10, 'YTickLabel', YTickStr);

[AA]

Thanks for sharing a detialed answer,

I got an error "Undefined function 'string' for input arguments of type 'datetime'."

*I am using Matlab 2016a

Here is the modified code,

data information:

day 1*1420 double

time 1*3001 double (this case has -300:300)

z2 1420*3001 double

    fig=figure(ii);
    h1=subplot(3,1,1);
    imagesc(time,day,z2);
    colormap(jet)
    YTickStr = string(datetime('10/10/2018', 'InputFormat', 'dd/MM/yyyy', 'Format', 'dd/MM/yyyy') + hours(day*12));
    set(gca, 'XTick', -300:50:300, 'XTickLabel','YTick', 1:lastday, 'YTickLabel', YTickStr);

[Chunru]

Then change string to char.

[AA]

Thanks boss :) but

Error using matlab.graphics.axis.Axes/set
Invalid parameter/value pair arguments.
Error in plot_CF (line 55)
set(g
ca, 'XTick', -300:50:300, 'XTickLabel','YTick', 1:lastday, 'YTickLabel', YTickStr);

[Chunru]

You miss simething after 'XTickLabel'.

[AA]

thank you very much, it works.

[AA]

I found a problem with y-axis. if possible, please leave a comment

If i do not change the interval , it gives me so many values but later i changed the interval then it started from 1 JAN.

YTickStr:

10/10/18

10/10/18

10/10/18

11/10/18

11/10/18

11/10/18

11/10/18

12/10/18

12/10/18

12/10/18

12/10/18

13/10/18

13/10/18

Total segmetns lengths are : 1:1524

 imagesc(time,day,z2);
    colormap(jet)
    YTickStr = char(datetime('10/10/2018', 'InputFormat', 'dd/MM/yy', 'Format', 'dd/MM/yy') + hours(day*6));
    set(gca, 'YTick', 1:500:lengday, 'YTickLabel', YTickStr);
    xlim([-100 100]);

here is output example for these format (without interval, 1:lengday)

with interval (1:500:lengday), it starts from 1 jan

Answer 2

[KSSV]

A = [1	0
2	0
3	0
4	0.199999999999996
5	0
6	0
7	0
8	0.199999999999996
9	0
10	0
11	0
12	0];

t0 = datetime('10/10/2018') ;

[r,c] = size(A);
N  =  size(A,1)/2 ;  % number of hours in a day
B   = permute(reshape(A',[c,r/N,N]),[2,1,3]);
tn = t0+days(N) ;
t = (t0:tn)' ;

Each matrix in B corresponds to respective day in t.

Answer 3

[Cris LaPierre]

If you convert your data to datetime, then you can set the y axis format to be any valid date format.

data = [1	0
2	0
3	0
4	0.199999999999996
5	0
6	0
7	0
8	0.199999999999996
9	0
10	0
11	0
12	0];
dataTT = array2timetable(data(:,2),'RowTimes',datetime(2018,10,10) + 12*hours(data(:,1)-1))

dataTT = 12×1 timetable
            Time            Var1
    ____________________    ____

    10-Oct-2018 00:00:00      0 
    10-Oct-2018 12:00:00      0 
    11-Oct-2018 00:00:00      0 
    11-Oct-2018 12:00:00    0.2 
    12-Oct-2018 00:00:00      0 
    12-Oct-2018 12:00:00      0 
    13-Oct-2018 00:00:00      0 
    13-Oct-2018 12:00:00    0.2 
    14-Oct-2018 00:00:00      0 
    14-Oct-2018 12:00:00      0 
    15-Oct-2018 00:00:00      0 
    15-Oct-2018 12:00:00      0 

plot(dataTT.Var1,dataTT.Time)
ytickformat('MM/dd/yyyy')