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R: If operator function using

I have the following framework:

ID  Value
1    0
2   100
3   200
4    0

I want to write a function that produces "Hello" if the value in the "Value" column is 0, otherwise "Bye". The result should be:

Answer
Hi
Bye
Bye
Hi

Here is the code I tried:

Type <- function(df){
  if(df$Value == 0)
    "Hi"
  else
    "Bye"
}

apply(X = df, MARGIN = 1, FUN = Type)

However, I am getting this error:

Error in Test_Customer$Pipe : $ operator is invalid for atomic vectors

Can anyone help me fix this error? Thank you!

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2 answers


apply()

is intended for use with matrices, not data frames. It will actually convert your data.frame to a matrix. So when it is executed, it traverses in rows or columns as simple atomic vectors. It does not augment data.frames. You cannot use $

with atomic vectors, hence your error message.

You don't need one apply()

for your example. Simple ifelse()

will work



ifelse(df$Value==0, "Hi,"Bye")

The function is ifelse()

vectorized to work on a column of data at a time. (The operator is if

not vectorized).

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You may try

 c('Bye', 'Hi')[(df1$Value==0)+1L]
 #[1] "Hi"  "Bye" "Bye" "Hi"


Or use factor 

factor(df1$Value!=0, labels=c('Hi', 'Bye'))
#[1] Hi  Bye Bye Hi 
#Levels: Hi Bye
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