Merge pull request #57 from brymz/Graphing-3

Graphing 3

exercises/Graphing-3-R.md

@@ -0,0 +1,28 @@
+---
+layout: exercise
+title: Graphing 3
+language: R
+---
+
+It makes sense that larger organisms have larger offspring, but what the
+mathematical form of this relationship should be is unclear. Let's
+look at the problem empirically for mammals.
+
+Download some
+[mammal life history data](http://esapubs.org/archive/ecol/E084/093/Mammal_lifehistories_v2.txt) from the web. 
+You can do this either directly in the program using `read.csv()` or download 
+the file to your computer using your browser and import it from there.
+
+When you import the data there are some extra blank lines at
+the end of this file. Get rid of them by using the optional `read.csv()`
+argument to select the valid 1440 rows, `nrows = 1440`.
+
+Missing data in this file is specified by -999 and -999.00. Tell R that
+these are null values using the optional `read.csv()` argument,
+`na.strings = c("-999", "-999.00")`. This will stop them from being plotted.
+
+1. Graph adult mass vs. newborn mass. Label the axes.
+2. Graph the log (base 10) of adult mass vs. the log (base 10) of
+   newborn mass. Label the axes.
+3. For data where `order` is `"Rodentia"`, graph the log (base 10) of adult mass
+   vs. the log (base 10) of newborn mass. Label the axes.