left_join: Join two data frames, keeping all the rows in the left table

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Join two data frames, keeping all the rows in the left table

Description

Use left_join() to combine two data frames by a key. A key is a variable that the two data frames have in common.

Usage

left_join(x, y, by = NULL)

Arguments

x	The left data frame. All the rows will be kept.
y	The right data frame. Only the rows which correspond to the rows in x will be kept.
by	A character vector that specifies which variables are the keys.

Examples

# Suppose you have two data sets:

# The first one has census-type information
# on people:

people <- tibble(
  name = c("Anne", "Bruce", "Carlos"),
  sex = c("F", "M", "M"),
  birthdate = c("19920206", "19820405", "20001226"),
  ssn = c(123, 456, 789)
)

# The second data set has car registration
# information on some of the same people:

drivers <- tibble(
  name = c("Bruce", "Carlos", "Danielle"),
  license_no = c(431, 765, 234),
  social_security = c(456, 789, 101),
  car_make = c("Jeep", "Acura", "Toyota")
)

# Note that 'name' and 'ssn', which corresponds
# to 'social_security', are in both datasets.
# We'll use both of these variables as keys.

left_join(
  people,
  drivers,
  by = c("ssn" = "social_security", "name")
)

A tibble: 3 x 6
  name   sex   birthdate   ssn license_no car_make
  <chr>  <chr> <chr>     <dbl>      <dbl> <chr>
1 Anne   F     19920206    123         NA NA
2 Bruce  M     19820405    456        431 Jeep
3 Carlos M     20001226    789        765 Acura

cobriant/qelp documentation built on July 1, 2022, 7:24 a.m.