CODEWITHSUNDEEP
r
Sandeep
Sandeep

Reputation: 71

Changing values of few columns in R

I have a dataset where I want to change values of few columns. This is a dummy dataset

A <- c(1, 2, 1, 0, 1, 2)
B <- c(0, 2, 2, 0, 1, 1)
C <- c(1, 2, 1, 0, 1, 0)

Here D is the dataset containing A, B, C column

D <- data.frame(A, B, C)

Here I want to replace values of A and C.

1 will be 1

2 will be 0

0 will be 2

New dataframe should be having simialr results for A and C

A = c(1, 0, 1, 2, 1, 0)

C = c(1, 0, 1, 2, 1, 2)

Hence, I wrote a function

A2_risk <- function(x){
  2 - x
}

Function works perfectly when I call just vectors.

When I am trying to write a for loop or apply function, it is creating issues. lapply function converts it into list not in a dataframe. Real dataset has many columns to be converted. Hence, I need a function or loop to do everything in one shot.

Thank you

Upvotes: 0

Views: 50

Answers (3)

WilliamGram
WilliamGram

Reputation: 683

As an alternative you can use purrr:

library(purrr)
data.frame(map_if(D, names(D) %in% c('A', 'C'), ~ 2-.x))
#   A B C
# 1 1 0 1
# 2 0 2 0
# 3 1 2 1
# 4 2 0 2
# 5 1 1 1
# 6 0 1 2

Upvotes: 1

user2974951
user2974951

Reputation: 10375

Edit:

A2_risk <- function(i){
  if (kol[i]) {
    D[,i]
  } else {
    2-D[,i]
  }
}

kol=grepl("B",colnames(D))

sapply(1:ncol(D),A2_risk)

     [,1] [,2] [,3]
[1,]    1    0    1
[2,]    0    2    0
[3,]    1    2    1
[4,]    2    0    2
[5,]    1    1    1
[6,]    0    1    2

If you wanted say B and C you would use kol=grepl("B|C",colnames(D)).

Upvotes: 0

Maurits Evers
Maurits Evers

Reputation: 50668

Using dplyr you can do

library(dplyr)
D %>% mutate(across(c(A, C), A2_risk))
#  A B C
#1 1 0 1
#2 0 2 0
#3 1 2 1
#4 2 0 2
#5 1 1 1
#6 0 1 2

Or in base R

mapply(function(col, nm) if (nm %in% c("A", "C")) A2_risk(col) else col, D, names(D))

Upvotes: 2

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