Plotting monthly precipitation and time

Hello There, Essentially I'm trying to plot x (time) and y (precipitation). x = [7/15/05 8/9/05 9/15/05 10/16/05 11/17/05 12/28/05 3/8/06 4/12/06 5/13/06 6/17/06 7/16/06 8/9/06 9/10/06 10/9/06 11/4/06 11/29/06 1/2/07];

y = [2.9 0.51 21.49 25.76 13.16 8.46 11.1 3.38 4.85 14.20 3.05 1.45 19.290 0.20 1.17 0.00 7.67];

The code i'm using is: figure(1) plot(x,y);grid;datetick('x','mm/dd/yyyy')

However my x axis is not plotting on the correct scale (attached figure). I seem to be missing a step. Any suggestions would be helpful! Cheers,

[Von Duesenberg]

Hi. Perhaps you could post your code exactly as you typed it in Matlab (I copied and pasted your example but wasn't able to replicate your figure).

Answer 1

[Peter Perkins]

In R2014b or later, use datetimes, not datenums:

>> x = {'7/15/05' '8/9/05' '9/15/05' '10/16/05' '11/17/05' '12/28/05' '3/8/06' '4/12/06' '5/13/06' '6/17/06' '7/16/06' '8/9/06' '9/10/06' '10/9/06' '11/4/06' '11/29/06' '1/2/07'}
x =
  1×17 cell array
  Columns 1 through 9
    '7/15/05'    '8/9/05'    '9/15/05'    '10/16/05'    '11/17/05'    '12/28/05'    '3/8/06'    '4/12/06'    '5/13/06'
  Columns 10 through 17
    '6/17/06'    '7/16/06'    '8/9/06'    '9/10/06'    '10/9/06'    '11/4/06'    '11/29/06'    '1/2/07'
>> t = datetime(x,'InputFormat','MM/dd/yy')
t = 
  1×17 datetime array
Columns 1 through 9
   15-Jul-2005   09-Aug-2005   15-Sep-2005   16-Oct-2005   17-Nov-2005   28-Dec-2005   08-Mar-2006   12-Apr-2006   13-May-2006
Columns 10 through 17
   17-Jun-2006   16-Jul-2006   09-Aug-2006   10-Sep-2006   09-Oct-2006   04-Nov-2006   29-Nov-2006   02-Jan-2007
>> y = [2.9 0.51 21.49 25.76 13.16 8.46 11.1 3.38 4.85 14.20 3.05 1.45 19.290 0.20 1.17 0.00 7.67];
>> plot(t,y)

[Natasha Sekhon]

Thank you for the tip! A quick follow up question: What if i had years for the 20th century, i.e., 1905 1906 and onwards. What should i do then?

Answer 2

[Ed Marquez]

Hi, I am assuming you are using MATLAB R2014b or later. My understanding is that you would like to plot the values contained in 'y' (precipitation data) versus the values contained in x, which are dates.

First you will need to redefine your 'x' vector to be a cell array containing characters, as shown below:

x = {'7/15/05';'8/9/05';'9/15/05';'10/16/05';'11/17/05';'12/28/05';'3/8/06';'4/12/06';'5/13/06';...
'6/17/06';'7/16/06';'8/9/06';'9/10/06';'10/9/06';'11/4/06';'11/29/06';'1/2/07'};

The 'y' vector you are using can stay as is.

After that you can try the code below:

a = datenum(x);
b = datestr(x,'mmm-dd-yyyy');

figure(1)
axObj = axes;

plot(a,y);
grid;
datetick('x','mm/dd/yyyy')
axObj.XTick = (a);
axObj.XTickLabels = (b);
axObj.XTickLabelRotation = 45;

[Peter Perkins]

Just in case it wasn't clear from Ed's post, x in the OP's code is very different than intended:

>> x = [7/15/05 8/9/05]
x =
     0.093333      0.17778

Without enclosing quotes, those slashes are divisions.