Subsetting rows and columns in R

Filtering and selecting with base R brackets.

heavy <- mtcars[mtcars$wt > 3.5, ]
two_cols <- mtcars[, c("mpg", "cyl")]
both <- mtcars[mtcars$cyl == 4, c("mpg", "wt")]

efficient <- subset(mtcars, mpg > 25, select = c(mpg, wt))
ordered <- mtcars[order(-mtcars$mpg), ]
top_five <- head(ordered, 5)

count <- nrow(heavy)

How it works

1. df[condition, ] keeps matching rows.
2. df[, cols] keeps named columns; both combine.
3. subset and order filter and sort more readably.

Keywords and builtins used here

• c
• head
• nrow
• order
• subset

The run, in numbers

Lines

9

Characters to type

271

Tokens

90

Three-star pace

90 tpm

At the three-star pace of 90 tokens a minute, this run takes about 60 seconds.

Type this snippet

Step 2 of 3 in Building & inspecting, step 2 of 8 in Data frames in base R.

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