Plot data with time

I'm trying to plot my data with time on the x-axis. My data has the following csv format:

13:05:48  1.33  5.15
13:05:53  2  5.2
13:05:58  2.1  4.88

There are 3 columns with column 1 being my time(HH:MM:SS) and column 2 and 3 being my data. How do I read then plot Column 1 time vs. my column 2 or 3?

Answer 1

[dpb]

[d,x,y]=textread('ivan.csv','%8s %f %f','delimiter',' ');
dn=datenum(d,'HH:MM:SS');  % ERRATUM: had lowercase in time format string
plot(dn,[x y])
datetick('x')

Alternatively, use textscan or with the latest releases there's a new datetime object

[Ivan Q]

I was getting some errors so I rewrote the code to this:

fid = fopen( 'file.txt' );
A=textscan(fid,'%8s %f %f');
x=A{2};
y=A{3};
dn=datenum(A{1},'hh:mm:ss');
plot(dn,y)
datetick('x','HH:MM:SS')

However, dn cycles between values of 7.3706 and 7.3606 and my x-axis does not show up as a time. How do I get the X-axis to display my exact time strings ie. 13:58:38

[Ivan Q]

I was able to accomplish what I wanted with the following code:

%%Open data and separate cells
fid = fopen( 'Data.txt' );
A=textscan(fid,'%8s %f %f');
x=A{2};
y=A{3};
dn=datenum(A{1},'HH:MM:SS'); %change string into datenum 

%%plot figure
plot(dn,x*2)
hold on
plot(dn,y)

%%Set x-axis
l=length(dn)
set(gca, 'XTick', (dn(1) : .001 : dn(l)) )
datetick('x','HH:MM:SS','keepticks')

[dpb]

Ah, yes, I carelessly used lower case for the time fields in the format string; that's an error, sorry. Checked that the textread worked right but didn't actually look a the the returned times on the axes, only that they were actually formatted as dates...I fixed up the Answer altho you've uncovered the problem.

I tend to use textread where I can even though it has been relegated to "red-haired stepchild" status by TMW as it doesn't require the extra step of fopen/fclose and returns char and double arrays where don't need or want cell arrays. It does require a separate variable for each field which can be a nuisance and can't handle all cases that textscan can, but for simple file structures it's a better option imo still. Anyway, that's an aside not related to the actual problem here...