CODEWITHSUNDEEP
rdynamicnames
little girl
little girl

Reputation: 295

Dynamic column name in for loop

I have problem with my code. I have data frame like this:

A <- c(21, 234, NA, 286,NA)
B <- c(3,NA,NA, 8, 10)
data <- data.frame(A,B)
data

    A  B
1  21  3
2 234 NA
3  NA NA
4 286  8
5  NA 10

And the effect I want to create is:

    A  B A_NA B_NA
1  21  3    0    0
2 234 NA    0    1
3  NA NA    1    1
4 286  8    0    0
5  NA 10    1    0

Here is my simple code, but something doesn't work..

for(i in c(1:ncol(data)))
  {
    data[, ncol(data) + 1] <- ifelse(is.na(data[i]), 1, 0)
    names(data)[ncol(data)] <- paste0(colnames(data[i]), "_NA")
  }

because effect is:

    A  B A A B A A
1  21  3 0 0 0 0 0
2 234 NA 0 0 1 0 0
3  NA NA 1 1 1 0 0
4 286  8 0 0 0 0 0
5  NA 10 1 1 0 0 0

Upvotes: 1

Views: 2005

Answers (2)

amonk
amonk

Reputation: 1795

Adding columns based on a condition:

 data$A_NA<-ifelse(is.na(data$A),1,0)
 data$B_NA<-ifelse(is.na(data$B),1,0)

addition

Recursively: 

for(nm in names(data))
  eval(parse(text = paste0("data$",nm,"_NA<-ifelse(is.na(data$",nm,"),1,0)")))

addition2

Alternatively one can use: 

for(nm in names(data)){
  assign(paste0(nm,"_NA"), ifelse(is.na(data[nm]),1,0))
  tempo<-data.frame(get(paste0(nm,"_NA")));names(tempo)<-paste0(nm,"_NA")
  data<-cbind(data,tempo)
}

Upvotes: 0

akrun
akrun

Reputation: 886938

We can use lapply to loop over the columns of 'data', check whether the elements are NA (is.na(x)), convert to integer (as.integer) and assign the output to new columns

data[paste0(names(data), "_NA")] <- lapply(data, function(x) as.integer(is.na(x)))
data
#    A  B A_NA B_NA
#1  21  3    0    0
#2 234 NA    0    1
#3  NA NA    1    1
#4 286  8    0    0
#5  NA 10    1    0

Upvotes: 2

Related Questions