Introduction
NYC Flights 13
library(nycflights13)
Keys
Mutating Joins
x <- tribble(
~key, ~val_x,
1, "x1",
2, "x2",
3, "x3"
)
y <- tribble(
~key, ~val_y,
1, "y1",
2, "y2",
4, "y3"
)
inner_join(x, y)
## Joining, by = "key"
## # A tibble: 2 × 3
## key val_x val_y
## <dbl> <chr> <chr>
## 1 1 x1 y1
## 2 2 x2 y2
Outer Join
left_join(x, y, by = "key")
## # A tibble: 3 × 3
## key val_x val_y
## <dbl> <chr> <chr>
## 1 1 x1 y1
## 2 2 x2 y2
## 3 3 x3 <NA>
right_join(x, y)
## Joining, by = "key"
## # A tibble: 3 × 3
## key val_x val_y
## <dbl> <chr> <chr>
## 1 1 x1 y1
## 2 2 x2 y2
## 3 4 <NA> y3
full_join(x, y)
## Joining, by = "key"
## # A tibble: 4 × 3
## key val_x val_y
## <dbl> <chr> <chr>
## 1 1 x1 y1
## 2 2 x2 y2
## 3 3 x3 <NA>
## 4 4 <NA> y3
Defining the key columns
flights %>% left_join (planes)
## Joining, by = c("year", "tailnum")
## # A tibble: 336,776 × 26
## year month day dep_time sched_de…¹ dep_d…² arr_t…³ sched…⁴ arr_d…⁵ carrier
## <int> <int> <int> <int> <int> <dbl> <int> <int> <dbl> <chr>
## 1 2013 1 1 517 515 2 830 819 11 UA
## 2 2013 1 1 533 529 4 850 830 20 UA
## 3 2013 1 1 542 540 2 923 850 33 AA
## 4 2013 1 1 544 545 -1 1004 1022 -18 B6
## 5 2013 1 1 554 600 -6 812 837 -25 DL
## 6 2013 1 1 554 558 -4 740 728 12 UA
## 7 2013 1 1 555 600 -5 913 854 19 B6
## 8 2013 1 1 557 600 -3 709 723 -14 EV
## 9 2013 1 1 557 600 -3 838 846 -8 B6
## 10 2013 1 1 558 600 -2 753 745 8 AA
## # … with 336,766 more rows, 16 more variables: flight <int>, tailnum <chr>,
## # origin <chr>, dest <chr>, air_time <dbl>, distance <dbl>, hour <dbl>,
## # minute <dbl>, time_hour <dttm>, type <chr>, manufacturer <chr>,
## # model <chr>, engines <int>, seats <int>, speed <int>, engine <chr>, and
## # abbreviated variable names ¹sched_dep_time, ²dep_delay, ³arr_time,
## # ⁴sched_arr_time, ⁵arr_delay
flights %>% left_join (planes, by = "tailnum")
## # A tibble: 336,776 × 27
## year.x month day dep_time sched_d…¹ dep_d…² arr_t…³ sched…⁴ arr_d…⁵ carrier
## <int> <int> <int> <int> <int> <dbl> <int> <int> <dbl> <chr>
## 1 2013 1 1 517 515 2 830 819 11 UA
## 2 2013 1 1 533 529 4 850 830 20 UA
## 3 2013 1 1 542 540 2 923 850 33 AA
## 4 2013 1 1 544 545 -1 1004 1022 -18 B6
## 5 2013 1 1 554 600 -6 812 837 -25 DL
## 6 2013 1 1 554 558 -4 740 728 12 UA
## 7 2013 1 1 555 600 -5 913 854 19 B6
## 8 2013 1 1 557 600 -3 709 723 -14 EV
## 9 2013 1 1 557 600 -3 838 846 -8 B6
## 10 2013 1 1 558 600 -2 753 745 8 AA
## # … with 336,766 more rows, 17 more variables: flight <int>, tailnum <chr>,
## # origin <chr>, dest <chr>, air_time <dbl>, distance <dbl>, hour <dbl>,
## # minute <dbl>, time_hour <dttm>, year.y <int>, type <chr>,
## # manufacturer <chr>, model <chr>, engines <int>, seats <int>, speed <int>,
## # engine <chr>, and abbreviated variable names ¹sched_dep_time, ²dep_delay,
## # ³arr_time, ⁴sched_arr_time, ⁵arr_delay
Filtering Joins
semi_join(x, y)
## Joining, by = "key"
## # A tibble: 2 × 2
## key val_x
## <dbl> <chr>
## 1 1 x1
## 2 2 x2
semi_join(y, x)
## Joining, by = "key"
## # A tibble: 2 × 2
## key val_y
## <dbl> <chr>
## 1 1 y1
## 2 2 y2
anti_join(x, y)
## Joining, by = "key"
## # A tibble: 1 × 2
## key val_x
## <dbl> <chr>
## 1 3 x3
anti_join(y, x)
## Joining, by = "key"
## # A tibble: 1 × 2
## key val_y
## <dbl> <chr>
## 1 4 y3
Join Problems
airports %>% count(name) %>% arrange(desc(n))
## # A tibble: 1,440 × 2
## name n
## <chr> <int>
## 1 Municipal Airport 5
## 2 All Airports 3
## 3 Capital City Airport 2
## 4 Dillingham 2
## 5 Douglas Municipal Airport 2
## 6 Executive 2
## 7 Grand Canyon West Airport 2
## 8 Jefferson County Intl 2
## 9 Marshfield Municipal Airport 2
## 10 Penn Station 2
## # … with 1,430 more rows
left_join (x, y)
## Joining, by = "key"
## # A tibble: 3 × 3
## key val_x val_y
## <dbl> <chr> <chr>
## 1 1 x1 y1
## 2 2 x2 y2
## 3 3 x3 <NA>
Set Operations
df1 <- tribble(
~x, ~y,
1, 1,
2, 1
)
df2 <- tribble(
~x, ~y,
1, 1,
1, 2
)
intersect(df1, df2)
## # A tibble: 1 × 2
## x y
## <dbl> <dbl>
## 1 1 1
union(df1, df2)
## # A tibble: 3 × 2
## x y
## <dbl> <dbl>
## 1 1 1
## 2 2 1
## 3 1 2
setdiff(df1, df2)
## # A tibble: 1 × 2
## x y
## <dbl> <dbl>
## 1 2 1