Practical Data Wrangling

Rewriting code using dplyr

In the previous chapter, R was used to find the estimate of the total road length in 2011. Here are the steps that were completed in the previous chapter, written using dplyr verbs:

• Filter out the rows with a mean greater than 2000
• Filter out the rows in which all values are NA
• Mutate the 2011 column to create a copy in which the NA values are replaced with the row mean
• Select the new 2011 column and find the sum of its values

At the beginning of dplyr_intro.R, the first step should be to read artificial_roads_by_region.csv to an R dataframe as follows:

roads.lengths <- read.csv("data/artificial_roads_by_region.csv")

Next, In the following continuation of dplyr_intro.R, a copy of the original roads length data ...