CODEWITHSUNDEEP
rdata.table
asbebe
asbebe

Reputation: 71

How to set multiple columns and selected rows in data table to value from other data table

The Question is somewhat related with this question (How to set multiple columns in a data table to values from different columns in the same data table?).

set.seed(1)
df <- data.frame(matrix(sample(1:100,30),ncol=6))
#  X1 X2 X3 X4 X5 X6
#1 27 86 19 43 75 29
#2 37 97 16 88 17  1
#3 57 62 61 83 51 28
#4 89 58 34 32 10 81
#5 20  6 67 63 21 25
library(data.table)
dt <- data.table(df)


df1 <- data.frame(matrix(sample(1:100,30),ncol=6))
df1
#   X1 X2 X3 X4 X5 X6
#1  49 64 74 68 39  8
#2  60 75 58  2 88 24
#3 100 11 69 40 35 91
#4  19 67 98 61 97 48
#5  80 38 46 57  6 29
dt1 <- data.table(df1)

This time, I want to change the certain row and column.

dt[1:3, c("X1","X2"), with = F] = dt1[1:3, c("X3","X5"), with = F]

But this one give an error:

Error in `[<-.data.table`(`*tmp*`, 1:3, c("X1", "X2"), with = F, value = list( : 
  unused argument (with = F)

I will do with the data had many columns. I hope that the name of column should be character at first.

Upvotes: 0

Views: 1037

Answers (1)

Jaap
Jaap

Reputation: 83265

By using the = operator as you do, you are trying assign the values to the desired spots in the data.table. Instead you should update your data.table dt by reference with the := operator inside dt[...]. A slight adaptation of @thelatemail's comment (the second with = FALSE is not needed):

dt[1:3, c("X1","X2") := dt1[1:3, c("X3","X5"), with = FALSE]]

Upvotes: 2

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