Merge pull request #1053 from ethanwhite/r-intro-update

Add challenge exercise for vectors

assignments/r-intro.md

@@ -4,8 +4,8 @@ layout: page
 element: assignment
 title: Introduction to R and RStudio
 language: R
-exercises: ['Basic Expressions', 'Basic Variables', 'More Variables', 'Built-in Functions', 'Modify the Code', 'Basic Vectors', 'Nulls in Vectors', 'Shrub Volume Vectors', 'Check That Your Code Runs', 'Variable Names']
-points: [10, 10, 10, 10, 10, 10, 15, 15, 10, optional]
+exercises: ['Basic Expressions', 'Basic Variables', 'More Variables', 'Built-in Functions', 'Modify the Code', 'Basic Vectors', 'Nulls in Vectors', 'Shrub Volume Vectors', 'Check That Your Code Runs', 'Biomass vectors']
+points: [10, 10, 10, 10, 10, 10, 15, 15, 10, Challenge - optional]
 ---
 
 ### Learning Objectives

exercises/Vectors-biomass-vectors-R.md

@@ -0,0 +1,31 @@
+---
+layout: exercise
+topic: Vectors
+title: Biomass vectors
+language: R
+---
+
+You have data on the diameter of all of the trees in three sites and each site includes a mix of managmeent stratagies.
+Tree masses can be estimated using diameter based on the equation `mass = 0.124 * diameter ^ 2.53`.
+The biomass is the sum of the masses of all the trees at a site.
+Copy the vectors below into your R script.
+
+
+```r
+site <- c(1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3)
+diameter <- c(10.5, 14.2, 13.7, 15.3, 12.8, 9.8, 11.4, 10.9,
+               12.1, 13.5, 14.7, 8.5, 9.2, 10.1, 11.3, 12.4,
+               13.6, 14.8)
+management <- c("active", "active", "passive", "passive",
+                "active", "passive", "active", "active",
+                "passive", "passive", "active", "active",
+                "passive", "active", "passive", "active",
+                "passive", "active")
+```
+
+*Using only the tools we covered in class* and the information above, answer the following questions:
+
+1. What is the mass of the largest tree, which site is it in, and what is its management status?
+2. Which site has the greatest total biomass and what is that biomass?
+3. What is the average mass of a tree in each site?
+4. What is the difference in total biomass for each site between the "active" management and "passive" management strategies?

materials/r-intro.md

@@ -129,6 +129,7 @@ weight_g
 
 ### Assignments format
 
+* **SEPARATE FILES FOR CLASS CODE ALONG AND HOMEWORK**
 * Comment before each problem and each sub-problem
 * Make sure result prints out on `Source with echo`