using table() with for loop

class<- c('A','B')
var2<- c(1,0)
var3 <- c(0,1)

df<- data.frame(class,var2,var3)



for (i in colnames(df)[2:3])
{
#print(i)
table(paste0('df$',i), df$class)
}

results in error ‘all arguments must have the same length’. Also tried putting get(paste0('df$',i))

Is there a way to loop through these columns and tabulate?

>Solution :

The issue with your code is that because paste0() returns a character vector e.g, ‘var2’ and is not a correct argument for table() function. You can use the double bracket ‘[[‘ to extract the columns:

# create a list to save the results from loop
 tl<-vector(mode = 'list')
# run the loop and add the results for each column in the corresponding element of 'tl'

for (i in colnames(df)[2:3]) {
  tl[[i]]<-table(df[[i]], df$class)
}

output

tl

$var2
   
    A B
  0 0 1
  1 1 0

$var3
   
    A B
  0 1 0
  1 0 1

alternatively you can use lapply() function:

lapply(df[, 2:3], function(x) table(x, df$class))

var2
   
x   A B
  0 0 1
  1 1 0

$var3
   
x   A B
  0 1 0
  1 0 1