The semi_join and anti_join verbs

Joining Data with dplyr

Chris Cardillo

Data Scientist

Mutating verbs

inner_join
left_join
right_join
full_join

Review: left join

batmobile %>%
  left_join(batwing, by = c("part_num", "color_id"), suffix = c("_batmobile", "_batwing"))

# A tibble: 173 x 4
   part_num color_id quantity_batmobile quantity_batwing
   <chr>       <dbl>              <dbl>            <dbl>
 1 3023           72                 62               NA
 2 2780            0                 28               17
 3 50950           0                 28                2
 4 3004           71                 26                2
 5 43093           1                 25                6
 6 3004            0                 23                4
 7 3010            0                 21               NA
 8 30363           0                 21               NA
 9 32123b         14                 19               NA
10 3622            0                 18                2
# … with 163 more rows

Filtering joins

Keeps or removes observations from the first table
Doesn't add new variables
semi_join()
anti_join()

Filtering joins

Semi join

What observations in X are also in Y?

Filtering joins

Semi join

What observations in X are also in Y?

Anti join

What observations in X are not in Y?

The semi join

batmobile %>%
  semi_join(batwing, by = c("color_id", "part_num"))

# A tibble: 45 x 3
   part_num color_id quantity
   <chr>       <dbl>    <dbl>
 1 2780            0       28
 2 50950           0       28
 3 3004           71       26
 4 43093           1       25
 5 3004            0       23
 6 3622            0       18
 7 4286            0       16
 8 3039            0       12
 9 4274           71       12
10 3001            0       11
# … with 35 more rows

The anti join

batmobile %>%
  anti_join(batwing, by = c("color_id", "part_num"))

# A tibble: 128 x 3
   part_num color_id quantity
   <chr>       <dbl>    <dbl>
 1 3023           72       62
 2 3010            0       21
 3 30363           0       21
 4 32123b         14       19
 5 50950         320       18
 6 6541            0       18
 7 3040b           0       14
 8 3298            0       14
 9 3660            0       14
10 42022           0       14
# … with 118 more rows

Filtering with semi_join

themes %>%
  semi_join(sets, by = c("id" = "theme_id"))

# A tibble: 569 x 3
      id name           parent_id
   <dbl> <chr>              <dbl>
 1     1 Technic               NA
 2     2 Arctic Technic         1
 3     3 Competition            1
 4     4 Expert Builder         1
 5     5 Model                  1
 6     6 Airport                5
 7     7 Construction           5
 8     9 Fire                   5
 9    10 Harbor                 5
10    11 Off-Road               5
# … with 559 more rows

Filtering with anti_join

themes %>%
  anti_join(sets, by = c("id" = "theme_id"))

# A tibble: 96 x 3
      id name         parent_id
   <dbl> <chr>            <dbl>
 1     8 Farm                 5
 2    24 Airport             23
 3    25 Castle              23
 4    26 Construction        23
 5    27 Race                23
 6    28 Harbor              23
 7    29 Train               23
 8    32 Robot               23
 9    34 Building            23
10    35 Cargo               23
# … with 86 more rows

The joining verbs

inner_join
left_join
right_join

full_join
semi_join
anti_join

Let's practice!

Joining Data with dplyr