Software tutorial/Basic plots in R

From Statistics for Engineering
Jump to navigation Jump to search
The printable version is no longer supported and may have rendering errors. Please update your browser bookmarks and please use the default browser print function instead.
← Basic data manipulation in R (previous step) Tutorial index Next step: Plots with multiple series, colour, and legends →


<rst> <rst-options: 'toc' = False/> <rst-options: 'reset-figures' = False/> A simple sequence plot


We will continue on with the data set described in the previous section. Load the dataset and let's plot the column called ``Visits`` - there are 4 columns in the dataset, so we must be specific on which one to plot.

.. code-block:: s

website <- read.csv('http://openmv.net/file/website-traffic.csv') plot(website$Visits) Which produces this figure. Note that the defaults in R are to leave a lot of white space around the figure. We will show later how to remove that. </rst> [[Image: website-traffic-base.jpg|500px|center]] <rst> <rst-options: 'toc' = False/> <rst-options: 'reset-figures' = False/> That plot shows only the points (markers), in the order of the data set. What if you want lines between the points? Type ``help(plot)`` to find out more about the ``plot`` command. For example, it tells you there that ``type="p"`` will just show the points (the default setting for ``plot``): .. code-block:: s plot(website$Visits, type="p")


If you use ``type="l"`` you get a line plot:

.. code-block:: s

plot(website$Visits, type="l") and ``type="b"`` will show both lines and points, leaving a space between the point and the line connections .. code-block:: s plot(website$Visits, type="b")

and ``type="o"`` will connect (overplot) the lines and points.

Box plots


The basic boxplot syntax is:

.. code-block:: s

boxplot(website$Visits) To get boxplots for each day of the week, side-by-side we rely on the fact the column, ``DayOfWeek``, is a categorical variable. R calls these ``factor`` variables, and you can confirm this: ``is.factor(website$DayOfWeek)`` returns ``TRUE``. We can then tell the ``boxplot`` command to group the boxplots by a factor variable. Read the help text, ``help(boxplot)``, and ``help(factor)`` in order to understand more clearly how this plot was generated.

.. code-block:: s

boxplot(website$Visits ~ website$DayOfWeek)

</rst>

Website-traffic-boxplot-default.jpg
← Basic data manipulation in R (previous step) Tutorial index Next step: Plots with multiple series, colour, and legends →