How do i plot temperature vs date and time?

Hey

I´m trying to plot data from a matrix looking like this: 3 columns with several measurements each day at different times.

Day Time Temp 1 09:00 16 2 09:00 16.2

and so on.

I want to create a plot with temp on y axis and day AND time on the x axis. So far i managed to plot the temp vs time, but this generates a graph with many different lines but not separated by day som they all end upon top of each other.

I need a command that makes matlab differentiate between the days, not only the time.

Ive been looking at commands like xtick, datetick etc but i dont get how to create what im looking for using these commands.

Thanks in advance for tips and hints.

Answer 1

[Star Strider]

The datenum function might be what you need.

[Niclas Dahlman]

Thanks for your reply Star Strider. Going to try this later today, one prolem I think of is the separation of date and time in two different columns. Can i somehow merge column 1 and 2 so datenum uses all the information at once, both date and time? Maybe there is an easier way to sort the data?

Answer 2

[Andrei Bobrov]

file yourdata.txt have values:

Day      Time      Temp
1        09:00     16
2        09:00     16.2
...

solution

f = fopen('yourdata.txt');
c = textscan(f,'%f %s %f','HeaderLines',1);
fclose(f);
d = [c{1}-1 + rem(datenum(c{2},'HH:MM'),1), c{3}];