CODEWITHSUNDEEP
rdatatableassign
Mahmoud
Mahmoud

Reputation: 401

Update datatable columns with values from another datatable

Consider the following two data.tables:

df1=data.table(a=1:3, b=4:6, c=7:9)
df2=data.table(a=c(T,F,T), c=c(F,F,T), d=c(T,F,F))

What is the best way to update columns a and c of df1 with the corresponding values from df2?

df1[,c("a","c"),with=FALSE] and df2[,c("a","c"),with=FALSE] return the corresponding parts of each data.table;

but df1[,c("a","c"),with=FALSE] <- df2[,c("a","c"),with=FALSE] returns an error!

Upvotes: 0

Views: 48

Answers (1)

cardinal40
cardinal40

Reputation: 1263

Here's another solution:

library(tidyverse)

df1 <- tibble(a = 1:3, b = 4:6, c = 7:9)
df2 <- tibble(a = c(T,F,T), c = c(F,F,T), d = c(T,F,F))

bind_cols(df1, df2) %>% 
  transmute(a = a1, b, c = c1)

This creates a table with all six columns and then the transmute call selects and renames the ones you're interested in.

Upvotes: 1

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