r merge-tutorial
TRANSCRIPT
Question A = FieldGroup, SprFert
1, UAN282, UAN30
B = FieldGroup, FieldID, NO3N1, 2, 222, 3, 253, 4, 24
R Equivalent
output = merge(x = A, y = B,
all.y = TRUE) Default merges by
intersect(names(A), names(B))
R Equivalent
output = merge(x = A, y = B,
all.y = TRUE) Default merges by
intersect(names(A), names(B)) all.y ensures no records from y will be
dropped.
Default Join output =
merge(A, B) Will get:FieldGroup, FieldID, NO3N, SprFert
1, 2, 22, UAN282, 3, 25, UAN30
Default Join output =
merge(A, B) Will get:FieldGroup, FieldID, NO3N, SprFert
1, 2, 22, UAN282, 3, 25, UAN30
Known as “inner join” where only keep the records when both tables have a record.
Multiple records? A = FieldGroup, SprFert
1, UAN282, UAN30
B = FieldGroup, FieldID, NO3N1, 2, 221, 1, 202, 3, 253, 4, 24
Default Join output =
merge(A, B) Will get:FieldGroup, FieldID, NO3N, SprFert
1, 2, 22, UAN281, 1, 20, UAN282, 3, 25, UAN30