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How do I concatenate two columns in R? To concatenate two columns you can use the <code>paste()</code> function. For example, if you want to combine the two columns A and B in the dataframe df you can use the following code: <code>df['AB'] <- paste(df$A, df$B)</code>.
We can merge two data frames in R by using the merge() function or by using family of join() function in dplyr package. The data frames must have same column names on which the merging happens. Merge() Function in R is similar to database join operation in SQL.
semi_join() function: This function returns all rows from x where there are matching values in y, keeping just columns from x..
To join by different variables on x and y , use a named vector. For example, by = c("a" = "b") will match x$a to y$b . To join by multiple variables, use a vector with length > 1. For example, by = c("a", "b") will match x$a to y$a and x$b to y$b .
Updating to use tibble()
You can pass a named vector of length greater than 1 to the by argument of left_join():
library(dplyr)
d1 <- tibble(
x = letters[1:3],
y = LETTERS[1:3],
a = rnorm(3)
)
d2 <- tibble(
x2 = letters[3:1],
y2 = LETTERS[3:1],
b = rnorm(3)
)
left_join(d1, d2, by = c("x" = "x2", "y" = "y2"))
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