Question

I’m trying to plot values in matlab.

my csv file looks like this,

> 15.12.2012 11:27; 0.9884753
> 15.12.2012 11:12; 10.670.642
> 15.12.2012 10:57; 114.455.145
> 15.12.2012 10:42; 101.301.446
> 14.12.2012 10:27; 0.99031037
> 14.12.2012 10:12; 104.594.388
> 14.12.2012 09:57; 0.97192177
> 14.12.2012 09:42; 0.8925
> 14.12.2012 09:27; 0.8985693
> 14.12.2012 09:12; 0.955
> 14.12.2012 08:57; 0.95103529
> 13.12.2012 08:42; 0.95203444
> 13.12.2012 08:27; 0.955
> 13.12.2012 08:12; 0.95970876
> 13.12.2012 07:57; 0.95929422
> 13.12.2012 07:42; 0.95578656
> 13.12.2012 07:27; 0.955
> 12.12.2012 07:12; 0.955
> 12.12.2012 06:57; 0.95342687
> 12.12.2012 06:42; 0.955
> 12.12.2012 06:27; 0.955
> 12.12.2012 06:12; 0.95930485
> 11.12.2012 05:57; 0.95530825
> 11.12.2012 05:42; 0.96452381
> 10.12.2012 05:27; 0.9675
> 10.12.2012 05:12; 0.98778061
> 10.12.2012 04:57; 102.982.993

I ‘m reading ‘11.12.2012 04:57’; as string and then using datvec.

[Y, M, D, H, MN, S] = datevec(‘String’)

Just to make it clear again

Col1=String  % [Y, M, D, H, MN, S]
Col2= number % [0.9884753;...;102.982.993]

Now i want to plot second col2 with respect to first Col1 ([Y, M, d].

plot (Col2)

It works . In my example data I have more than a single value for the same day.
How can I label my plot with date that appear only once per day.

regards,

Answer 1

You can do something as listed below. Since the date strings are not so short, it looks nicer to render them rotated (with rotateticklabel).

str = {
  '15.12.2012 11:27';
  '15.12.2012 11:12';
  ...
  '10.12.2012 04:57'
};

num = [
  0.9884753;
  10.670642;
  ...
  102.982993
];

% find first occurrence of dates
[y,m,d,h,mn] = datevec(str,'dd.mm.yyyy HH:MM');
dn = datenum(y,m,d);
[~,ind] = unique(dn,'first');
ind = sort(ind);

% plot it nicely
plot(num);
ax = gca;
dstr = cellstr(datestr(dn,'dd.mm.yyyy'));
set(ax, 'XTick',ind, 'XTickLabel',dstr(ind), 'Position',[0.1,0.15,0.8,0.75]);
rotateticklabel(ax, 30);

And this is what you can get: