CODEWITHSUNDEEP
rdataframe
Chetan Arvind Patil
Chetan Arvind Patil

Reputation: 866

Compare Two Columns In A Data Frame And If False Then Capture Value of Another Column

I have a data set in which I want to compare two columns. For each row where these column don't match I want to capture the corresponding row value of another value and write it in another data frame.

Input Data

data <- structure(list(A = 1:7, B = c(1L, 2L, 1L, 1L, 1L, 9L, 9L), C = c(1L, 
3L, 2L, 1L, 6L, 8L, 1L)), class = "data.frame", row.names = c(NA, 
-7L))

Expected Output

  A
1 2
2 3
3 5
4 6
5 7

Currently I am using following code but this leads to empty rows when the value for B and C column matches in Input Data. I want to keep those of A for which B and C don't match.

Is it possible to it any another way so ensure above condition is met?

Code

ifelse(data$B == data$C, 
      data$A, "")

Output of Above Code

[1] ""  "2" "3" ""  "5" "6" "7"

Upvotes: 1

Views: 288

Answers (2)

akrun
akrun

Reputation: 887153

We can just use subset

subset(data, B != C, select = A)
#  A
#2 2
#3 3
#5 5
#6 6
#7 7

Or with filter

library(dplyr)
data %>% 
    filter(B != C) %>%
    select(A)

Or using data.table

library(data.table)
setDT(data)[B != C, .(A)]

Upvotes: 1

Ronak Shah
Ronak Shah

Reputation: 388982

You could select A values where B != C and then add it to a new data frame. 

data.frame(A = data$A[data$B != data$C])

#  A
#1 2
#2 3
#3 5
#4 6
#5 7

If you just need vector of values you could do

data$A[data$B != data$C]
#[1] 2 3 5 6 7

In ifelse we are replacing the values which do not satisfy the condition with empty space ("") hence the length of output is same as number of rows in data.

Upvotes: 1

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