.. _example_21:

(21) Time-series of RedHat stock price
--------------------------------------

As discussed in the Cookbook Section :ref:`cartesian_time_axes`, the annotation of time-series is
generally more complicated due to the extra degrees of freedom afforded
by the dual annotation system. In this example we will display the trend
of the stock price of RedHat (RHAT) from their initial public offering
until late 2006. The data file is a comma-separated table and the
records look like this:

::

    Date,Open,High,Low,Close,Volume,Adj.Close*
    12-Mar-04,17.74,18.49,17.67,18.02,4827500,18.02
    11-Mar-04,17.60,18.90,17.37,18.09,7700400,18.09

Hence, we have a single header record and various prices in USD for each
day of business. We will plot the trend of the opening price as a red
line superimposed on a yellow envelope representing the low-to-high
fluctuation during each day. We also indicate when and at what cost Paul
Wessel bought a few shares, and zoom in on the developments since 2004;
in the inset we label the time-axis in Finnish in honor of Linus
Thorvalds. Because the time coordinates are Y2K-challenged and the order
is backwards (big units of years come *after* smaller units like days)
we must change the default input/output formats used by GMT. Finally,
we want to prefix prices with the $ symbol to indicate the currency.
Here is how it all comes out:

.. literalinclude:: /_verbatim/example_21.txt
   :language: bash

which produces the plot in Figure, suggesting
Wessel has missed a few trains if he had hoped to cash in on the
Internet bubble...

.. figure:: /_images/example_21.*
   :width: 500 px
   :align: center

   Time-series of RedHat stock price since IPO.