CODEWITHSUNDEEP
rmax
AgusDam87
AgusDam87

Reputation: 97

How to exclude a value when comparing two columns for the max value in R

I have two columns: A and B, with values from 1 to 7 each. I need to get the maximum value between both columns EXCLUDING the value 7, how can I do that? OR In the case that A has 7 I keep the value of B, this would serve me more, for instance:

A <- c(1,1,1,3,2,4,2,5,6,7)
B <- c(7,3,6,7,4,1,6,7,3,4)
df <- data.frame(A, B)

Expected results: 1,3,6,3,4,4,6,5,6,4

Upvotes: 4

Views: 624

Answers (5)

tmfmnk
tmfmnk

Reputation: 39858

One option could be:

with(df, pmax(A * (A != 7), B * (B != 7)))

 [1] 1 3 6 3 4 4 6 5 6 4

To deal with missing values:

with(df, pmax(A * (A != 7), B * (B != 7), na.rm = TRUE))

Considering also negative values:

with(df, pmax(A * (A != 7)^NA, B * (B != 7)^NA, na.rm = TRUE))

Upvotes: 6

ThomasIsCoding
ThomasIsCoding

Reputation: 101247

Another base R option using pmax

> do.call(pmax, c(replace(df, df == 7, NA), na.rm = TRUE))
 [1] 1 3 6 3 4 4 6 5 6 4

or

> do.call(pmax, replace(df, df == 7, -Inf))
 [1] 1 3 6 3 4 4 6 5 6 4

Upvotes: 1

Anoushiravan R
Anoushiravan R

Reputation: 21908

Updated special thanks to dear @tmfmnk.

Maybe there is a better way of handling this problem but it instantly popped up in my mind to replace every 7 with the lowest possible value like 0 so that it does not affect the comparison. It also works with NA values.

library(dplyr)
library(purrr)

A <- c(1,1,1,3,2,4,2,5,6,7)
B <- c(7,3,6,7,4,1,6,7,3,4)

df <- tibble(A, B)

df %>%
  mutate(across(everything(), ~ replace(., . == 7, 0))) %>%
  mutate(ResultColumn = pmap_dbl(., ~ max(c(...), na.rm = TRUE)))


# A tibble: 10 x 3
       A     B ResultColumn
   <dbl> <dbl>        <dbl>
 1     1     0            1
 2     1     3            3
 3     1     6            6
 4     3     0            3
 5     2     4            4
 6     4     1            4
 7     2     6            6
 8     5     0            5
 9     6     3            6
10     0     4            4

Upvotes: 3

Aru Bhardwaj
Aru Bhardwaj

Reputation: 55

Here is the tidyverse example:

library(tidyverse)
A <- c(1,1,1,3,2,4,2,5,6,7)
B <- c(7,3,6,7,4,1,6,7,3,4)
        
df <- data.frame(A,B)
        
df %>% 
  filter(A != 7, B != 7) %>% 
  transform(ResultColumn = pmax(A,B))

Output:

enter image description here

Upvotes: 2

Ashish Baid
Ashish Baid

Reputation: 533

df$max <- ifelse(pmax(df$A,df$B)==7, pmin(df$A,df$B),pmax(df$A,df$B))

Upvotes: 0

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