Matlab - Multiple annual line plots

Author

Multiple annual line plots

Robert

2008-01-29, 8:14 pm

Generally, I would like to know how to plot many years of
annual time series data on the same plot (i.e. from Jan 1 to
Dec 31 on the x-axis).

I have a column of dates (daily observations -
1968/01/01...) and a column with the variable Q. I have
imported the data and have established the vectors (y, m, d,
Q). I was hoping there was some sort of grouping function I
could use on y and plot associated values of Q.

Thoughts?

Walter Roberson

2008-01-29, 11:05 pm

In article <fnok6a$aib$1@fred.mathworks.com>,
Robert <river_doctor@hotmail.com> wrote:
>Generally, I would like to know how to plot many years of
>annual time series data on the same plot (i.e. from Jan 1 to
>Dec 31 on the x-axis).
>
>I have a column of dates (daily observations -
>1968/01/01...) and a column with the variable Q. I have
>imported the data and have established the vectors (y, m, d,
>Q). I was hoping there was some sort of grouping function I
>could use on y and plot associated values of Q.

I don't understand how you want the plot to appear.

If you want to group y based upon Q, then

sortedvals = sortrows([Q(:),y(:)]);

then sortedvals rows will be [Q,y] pairs with the same values
of Q grouped together.
--
"I was very young in those days, but I was also rather dim."
-- Christopher Priest

Robert

2008-01-30, 8:20 pm

roberson@ibd.nrc-cnrc.gc.ca (Walter Roberson) wrote in
message <fnootg$fnp$1@canopus.cc.umanitoba.ca>...
> In article <fnok6a$aib$1@fred.mathworks.com>,
> Robert <river_doctor@hotmail.com> wrote:
>
> I don't understand how you want the plot to appear.
>
> If you want to group y based upon Q, then
>
> sortedvals = sortrows([Q(:),y(:)]);
>
> then sortedvals rows will be [Q,y] pairs with the same values
> of Q grouped together.
> --
> "I was very young in those days, but I was also rather
dim."
> -- Christopher Priest

Sorry, let me clarify. The data is daily mean discharge
data from a river. So the y axis will be Q and the x axis
days of the year starting Jan 1. I want to plot 30 lines
(hydrographs) on the same plot (one for each year). The
data is in two columns - date and Q and I have used datevec
to separate out y m d. Perhaps it is easier if I
transformed the data so rows=day of year and columns=year so
I would be open to know how to do that easily as well.

Roderick Pearson

2008-01-30, 11:14 pm

"Robert " <river_doctor@hotmail.com> wrote in message
<fnqene$g4r$1@fred.mathworks.com>...
> roberson@ibd.nrc-cnrc.gc.ca (Walter Roberson) wrote in
> message <fnootg$fnp$1@canopus.cc.umanitoba.ca>...
1 to[color=darkred]
m, d,[color=darkred]
function I[color=darkred]
values[color=darkred]
> dim."
>
>
> Sorry, let me clarify. The data is daily mean discharge
> data from a river. So the y axis will be Q and the x axis
> days of the year starting Jan 1. I want to plot 30 lines
> (hydrographs) on the same plot (one for each year). The
> data is in two columns - date and Q and I have used datevec
> to separate out y m d. Perhaps it is easier if I
> transformed the data so rows=day of year and columns=year so
> I would be open to know how to do that easily as well.
Robert you are on the right track. I find it easier to
visualize in my mind when my data is in columns such as
date, Q1,Q2,Q3,.... The real question is what exactly do you
want on the x axis. Do you want the day of year with no
reference to month or season? The most simple way is to
convert the dates to a MATLAB serial date, sort the Q matrix
from lowest to highest date, day one to day 365/366, and
create a column,doy=(1:1:length(yourdatamatrix)) and plot
the q's versus that column of numbers, plot(doy,Q(:,2:end)).
That gets the plot done. You probably will want a more
informative graph but you need to explain how informative
and what toolboxes to which you have access. That will
enable readers to give you more answers

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