Below are a set of exercises to get you practicing with R.

A. Manipulating Vector Data

Using subsetting syntax (square brackets), write code that completes the following using the vector y.

y <- c(3,2,15,-1,22,1,9,17,5)

  1. Display only the first value of y.

  2. Display the last value of y, in a way that would work if y were any length.

  3. Display only the values in y that are greater than the mean of y.

B. Manipulating Data Frames

*Write code that completes the following using the built in PlantGrowth data set:

  1. Print the data to the screen, and examine the data thoroughly.

  2. Look at the help file that describes the data.

  3. Sort whole dataset by the weights

  4. Calculate the proportion of plants that weight more than 5.

  5. Compare the means and standard deviations of the two treatments and the controls. Use indexing, Boolean logic, and the mean() and sd() functions.

  6. Create a new data frame that just contains the control data

  7. In the new data frame, permanently change the third entry of the weight column from 5.18 to 4.1