Plot date and time

I have date and time values that I'd like to use for my XTick values. The data is in an array that has date, time and price. I would like to plot my price across multiple days and each time interval, 5 minute intervals. How can I set this up? Is it possible to set XTick to every 1.5 hours or every 18 ticks?

This is what I have right now but it doesn't accomplish what I want:

the array is 415x3 set like [date time price]

date = datenum(date,'mm/dd/yy');
time = datenum(time,'HH:MM');
count = length(time);
plot(price, count)

Thanks for your help!

Answer 1

[Thomas]

If you have date and time as cell's in Vectors date in format cell{mm/dd/yy} time in format cell{HH:MM:SS}

1) concatenate them

dt_time=[date time];

2) convert cell to mat

dt_time_new=cell2mat(dt_time);

3) convert to datenum here

final_time=datenum(dt_time_new,'mm/dd/yyHH:MM:SS');

plot(final_time,price)

datetick('x','mm/dd','keepticks')  % or which ever format you want

[Trader]

Is there a way to do this if date and time are already in serial format?

[Thomas]

Can you show an example of date time array

[Trader]

I am using the import() function to pull data from a .csv file and then assigning the values to a structure "f" after converting the dates to serial values

import = importdata(full_path);

% the first column (starting from the second row) is the trading days in format mm/dd/yyyy.

idate = import.textdata(2:end,2);

itime = import.textdata(2:end,3);

f.date = datenum(idate,'mm/dd/yy');

f.time = datenum(itime,'HH:MM');

% Create OHLC matricies

f.price_close=import.data(:,4);

Thanks again for you help!

[Geoff]

That line f.time will not give you a sensible result. I tried this. You need to do:

f.time = mod(datenum(itime,'HH:MM'), 1);

Then you can use:

final_time = f.date + f.time;

Alternatively, you can do this (if you don't need to split date and time in the first place):

f.datetime = datenum( [idate ' ' itime], 'mm/dd/yy HH:MM');

[Geoff]

Oh, actually you probably can't do my last suggestion cos your strings are gonna be in a cell array. You could use cellfun, but given that you are asking how to apply Thomas' answer to your code which is nearly identical, maybe you should stay away from cellfun for now! =)

[Trader]

Geoff - Could you give me your suggestion on how to use cellfun to accomplish this? I'm interested in learning.

[KRUNAL]

Thomas I tried using it. It says datenum failed for line 23

This is my code.

 clc;
 clear all;

 orginf = '<filename>';

 sheet = 'Sheet1';

 for n =1:151
xlrange = ['C' num2str(n+1)];
a = xlsread (orginf,sheet,xlrange);
if a==1
  range = ['E' num2str(n+1)];
  range1 = ['F' num2str(n+1)];
  range2 = ['S' num2str(n+1)];
  [~,~,b] = xlsread(orginf,sheet,range);
  c = xlsread(orginf,sheet,range1);
  d = {datestr(c,'HH:MM:SS')};
  dt_time = [b,d];
 [~,~,mag] = xlsread(orginf,sheet,range2);
 mag_new = double(cell2mat(mag));
  dt_time_new=cell2mat(dt_time)

final_time=datenum(dt_time_new,'mm/dd/yyHH:MM:SS'); %line 23
plot(final_time,mag_new)
datetick('x','mm/dd','keepticks') 
end
end

and my data in the various columns are as follows :

 Stage    Magnitude     Date             Time
1             -1        06/10/2012       17:56:50
1             -3        06/10/2012       17:59:33
2             -2        06/11/2012       8:52:45
2             -5        06/11/2012       8:52:46
3             -3        06/12/2012       9:11:37
3             -4        06/12/2012       9:55:56
3             -1        06/12/2013       9:57:46
4             -5        06/12/2013       10:47:49
4             -2        06/12/2013       10:48:08
4             -4        06/12/2013       10:50:35
5             -3        06/12/2013       7:47:43
5             -1        06/12/2013       8:15:30
5             -2        06/12/2013       8:16:04

I am trying to plot magnitude v/s date time. Please suggest me what is wrong with it ?