Warning message: In if (DataIfElse$Cost == "R") { : the condition has length > 1 and only the first element will be used

[Rax83]

Hi,

I am new to R and may be this is a silly question, just wanted to check if multiple loops condition works with vector.

I have a csv file imported as data and I am trying to code something like if column = R then 1 elseif column = A then 2 else column = G then 3 in one column. I can successfully create it in three separate columns but unable to include condition in one.

Below Code:

DataIfElse <- read.csv("C:/Users/vickhzu/Downloads/DataSource_RTest.csv")
DataIfElse$Reporting<-as.Date(DataIfElse$Reporting,"%D/%M/%Y")
x=1
for (val in x) {
DataIfElse$P <- if(DataIfElse$Cost == "R" || DataIfElse$Schedule == "R"|| DataIfElse$Scope == "R") "R" else if(DataIfElse$Cost== "A"|| DataIfElse$Schedule== "A"|| DataIfElse$Scope== "A") "A" else if(DataIfElse$Cost== "G" || DataIfElse$Schedule== "G" || DataIfElse$Scope== "G") "G" else "Z"
x=x+1
}
view(DataIfElse)

This gives me an warning "Warning message: In if (DataIfElse$Cost == "R") { : the condition has length > 1 and only the first element will be used" and only updates first value in the column with desired result. Can anyone please help me resolve the same.

Any help is appreciated. Thanks

[FJCC]

The vectorized form of if is ifelse and you could chain those together. However, the dplyr package has the function case_when which uses a convenient syntax for effectively chaining together ifelse calls.

library(dplyr)
DF <- data.frame(Cost = c("X", "R", "Y", "T"), 
                 Schedule = c("A", "T", "X", "U"),
                 Scope = c("X", "T", "G", "Q"),
                 stringsAsFactors = FALSE)
DF
#>   Cost Schedule Scope
#> 1    X        A     X
#> 2    R        T     T
#> 3    Y        X     G
#> 4    T        U     Q

DF <- mutate(DF, P =
               case_when(
                 Cost == "R" | Schedule == "R" | Scope == "R" ~ "R",
                 Cost == "A" | Schedule == "A" | Scope == "A" ~ "A",
                 Cost == "G" | Schedule == "G" | Scope == "G" ~ "G",
                 TRUE ~ "Z"
               )
             )
DF
#>   Cost Schedule Scope P
#> 1    X        A     X A
#> 2    R        T     T R
#> 3    Y        X     G G
#> 4    T        U     Q Z

^{Created on 2020-02-04 by the reprex package (v0.3.0)}

[Rax83]

Hi FJCC,

Thank you for your revert.

I tried including the code and it worked, but the output is the same, it considers first value and provides entire column with the same value. Am I doing something wrong here! Thanks

Code:
DF <- data.frame(read.csv("C:/Users/R Dashboard/DataSource_RTest_Entire Data.csv"))
library(dplyr)
DF <- mutate(DF, P =
case_when(
DF$Cost =="R" || DF$Schedule == "R" || DF$Scope == "R" ~ "R",
DF$Cost =="A" || DF$Schedule == "A" || DF$Scope == "A" ~ "A",
DF$Cost =="G" || DF$Schedule == "G" || DF$Scope == "G" ~ "G",
TRUE ~ "Z"
)
)
DF

Output:

Looking forward to hear from you!.

Regards,

[Yarnabrina]

You are not using the same code as FJCC suggested. You have changed | to ||, and used Df$... instead of just column name inside case_when. You need not give dataframe name inside case_when.

Also, | and || are not same. The longer reports only one boolean based on 1st element, and the shorter returns a vector of booleans. I posted regarding this a while back, so I'm linking that below.

if_else not working as expected inside dplyr::mutate

Since OP asked why it happens, and not only how to rectify, let me add a small explanation to the answer of @valeri. @tlg265, if you see the documentation of logical operators (help("Logic", package = "base")), you'll see the following: & and && indicate logical AND and | and || indicate logical OR. The shorter form performs elementwise comparisons in much the same way as arithmetic operators. The longer form evaluates left to right examining only the first element of each vector. Evaluation proceeds only until the result is determined. The longer form is appropriate for programming control-flow and typically preferred in if clauses. In typical if situation, you'd want the cond…

Hope this helps.

[Rax83]

Thank you Anirban for the explanation!

I have changed my code and it runs successfully with desired result.

Thanks,
Rax