MATLAB Plotting a monthly data on a daily axis

0
votes

I have a plot that has 528 points on the x-axis. The x-axis is labelled by mmm yyyy. I want to plot data over it, but the data is in monthly form. I want to take each of the monthly data points and plot it at the beginning of the month as a dot. 

% Axis and plot
t = 731:1258; % 20120101 to 20130611
y = reshape(dataPoint_Anom1x1(:,:,731:end),[],1); % Size 528x1
x = datenum(2009, 12, 31) + t; % Convert t into serial numbers

plot(x, y); % Plot data

hold on

The part below is what I'm having trouble with. The dataPoint_Clim1x1 is size 12x1. (1,1) corresponds to January, (2,1) corresponds to February, etc. I need to plot the corresponding month's climatology point as a dot at the beginning of each month between January 2012 and June 2013. 

%%%% Plot climatology on the same graph
dataClim_1x1 = dataClim(u,v,:); % Array that only contains points 1 degree away from 72.5E and 67.25S
B = mean(dataClim_1x1);  % Average along the column
dataPoint_Clim1x1 = mean(B,2); % Average along the row

x_dataClim = ???
y_dataClim = reshape(dataPoint_Clim1x1, [],1); % Change dataPoint_Clim1x1 into a 1 column matrix 


plot(x_dataClim,y_dataClim) % y_dataClim is only 12x1.

So the plot command right above is wrong. Do I just need to somehow set up the x-axis so that it plots every month with datenum somehow? I don't want to use a secondary axis though.

2
matlabplot

2 Answers

1
votes

I think you just need to define your x coordinates of the points with

x_dataClim = datenum(2011, 1:12, 1);

This generates "the first of the month":

>> datestr(x_dataClim)

ans = 

01-Jan-2011
01-Feb-2011
01-Mar-2011
01-Apr-2011
01-May-2011
01-Jun-2011
01-Jul-2011
01-Aug-2011
01-Sep-2011
01-Oct-2011
01-Nov-2011
01-Dec-2011

The cool thing is that you can actually "go into next year" - so

>> datestr(datenum(2011, 11:14, 1)) 

ans =

01-Nov-2011
01-Dec-2011
01-Jan-2012
01-Feb-2012
0
votes

Here's what I ended up doing:

x = datenum(2011,1:30,1); % 30 months of data (2 and 1/2 years)
y_dataClim = reshape(dataPoint_Clim1x1, [],1); % Change dataPoint_Clim1x1 into a 1 column matrix 
y = cat(1, y_dataClim, y_dataClim, y_dataClim(1:6,:));
scatter(x,y, 50,'fill'); % Plot scatter plot