R if else with for loop

I would like to calculate a ratio (A / B = C). Then I want to assign a label for ratio. If the ratio equals 0 label gets "0". If value less than 1 label gets "1". Lastly ratio is greater than 1 label gets "2".

Here is the example data:

                    A            B         C
  1                 0        171.06  0.0000000
  2                 1             2  0.5
  3                 0        120.84  360.00000
  4                 0        308.07  0.0000000
  5                 0        243.06  0.0000000
  6                 0       876.015  0.0000000

Here is the function with loop:

targets <- function(data)
{
  label_df <- data[,c("A", "B")]
    label_df[is.na(label_df)] <- 0
    label_df["C"] <- (label_df["A"] / label_df["B"]) 
    for(i in 1:nrow(label_df))
    {
      if(label_df$C == 0){label_df[i,"C"] <- 0}

       else if(label_df$C < 1){label_df[i,"C"] <- 1}
       else {label_df[i,"C"] <- 2}
      }
return(as.data.frame(label_df))
    }

And here is the result. It shows all labels 0.

lab <- target(data)      
head(lab)      

                    A            B         C      label     
  1                 0        171.06  0.0000000    0
  2                 1             2  0.5          0
  3                 0        120.84  360.00000    0
  4                 0        308.07  0.0000000    0
  5                 0        243.06  0.0000000    0
  6                 0       876.015  0.0000000    0

I check the result with table() function and it just shows all data for label 0. There are no 1 or 2 labels. I couldn't figure out where the problem is. Any idea?