How to solve: the condition has length > 1 and only the first element will be used

Question

I use the following code to calculate tax using R. where two variable can be given as argument . When a data set is used i want to calculate tax based on the category. I am new to package development. Kindly help me solve this problem.

I get error when i insert a dataset only the first category is calculated and get this Waring message.

Warning message: In if (category == 1) { : the condition has length > 1 and only the first element will be used

IIT<- function(income,category) {
if (category == 1){
if (income > 0 && income <= 18200) {
tax <- 0
} else if (income > 18200 && income <= 37000) {
tax <- (income - 18200) * .10
} else if (income > 37000 && income <= 80000) {
tax <- 3572 + (income - 37000) * .20
} else if (income > 80000 && income <= 180000) {
tax <- 17547 + (income - 80000) * .30
} else if (income > 180000 && Inf) {
tax <- 54547 + (income - 180000) * .40
}
return(tax)}
else if (category==2){
if (income > 0 && income <= 18200) {
  tax <- 0
} else if (income > 18200 && income <= 37000) {
  tax <- (income - 18200) * .15
} else if (income > 37000 && income <= 80000) {
  tax <- 3572 + (income - 37000) * .25
} else if (income > 80000 && income <= 180000) {
  tax <- 17547 + (income - 80000) * .35
} else if (income > 180000 && Inf) {
  tax <- 54547 + (income - 180000) * .45
}
return(tax)
}
}

what are you "passing" to the function ? single values or arrays/data frames ? — lbusett, Feb 19 '17 at 10:47
What is `if (income && category == 1)` supposed to do and do you actually mean `if (category == 1)`? — Bernhard, Feb 19 '17 at 11:04
lets say datset has income and category, income: 25000,25000,30000,30000 category: 1,2,1,2 as stated in program 1 has diffrent set of slap for tax and 2 has diffrent set of rules for tax. — Sulthan, Feb 19 '17 at 11:07

Bernhard · Accepted Answer · 2017-02-19T12:23:20.807

First, try to keep things simple. Your syntax is more complicated than it needs to be. For a single pair of values, you could rephrase your function as:

single.IIT <- function(income, category) {
    if (income < 0) stop("Error in IIT: income must bei > 0.")
    if (category == 1){
        if (income <= 18200) return(0)
        if (income <= 37000) return((income - 18200) * .19)
        if (income <= 80000) return(3572 + (income - 37000) * .325)
        if (income <= 180000) return(17547 + (income - 80000) * .37)
        return(54547 + (income - 180000) * .45)
        }

    if (category==2){
        if (income <= 18200) return(0)
        if (income <= 37000) return((income - 18200) * .15)
        if (income <= 80000) return(3572 + (income - 37000) * .25)
        if (income <= 180000) return(17547 + (income - 80000) * .35)
        return(54547 + (income - 180000) * .45)
    }

    stop("ERROR in IIT: category must be either 1 or 2.")
}

You could spot errors more easily in the short version. As you want to do more than one pair of data at once, you need to vectorize this:

IIT <- Vectorize(single.IIT)

Now you can test it:

> IIT( income = c(23000, 500000, 0), category = c(1, 2, 1))
[1]    912 198547      0
> IIT( income = c(0, 0, 500, 500, 19000, 19000, 40000, 40000),
+      category = c(1, 2, 1, 2, 1, 2, 1, 2))
[1]    0    0    0    0  152  120 4547 4322
> IIT( income = c(0, 18000, -20), category = c( 1, 1, 1))
Error in (function (income, category)  : 
Error in IIT: income must bei > 0.
> IIT( income = c(0, 18000, 202), category = c( 1, 1, 5))
Error in (function (income, category)  : 
ERROR in IIT: category must be either 1 or 2.

EDIT: In the comments you asked how to use this with a dataframe:

expl <- data.frame(income = c(30000, 40000, 50000,60000),
                  bodyweight = c(75, 60, 45, 98),
                  nationality = c("F", "CH", "D", "AU"),
                  category = c(1, 2, 1, 2))
# we need the first and the fourth column in that dataframe
expl$tax <- IIT(expl[[1]], expl[[4]])
print(expl)
plot(tax ~ income, data = expl, col=category, pch=19)

Thank you so much it worked fine but when i import a dataframe frm spreadsheet . this doesnt work. can you say how to use it? — Sulthan, Feb 19 '17 at 11:53
Please don't write "doesn't work" but specify, what does not work. If you want to see, how a functions works with your data, please provide some data. For this time, I edited my answer to provide a sample dataframe and how to use it. — Bernhard, Feb 19 '17 at 12:25
I am sorry for using it. i have a spreadsheet with two column one with "Income " and other with "Category" now if i insert the spreadsheet in to R environment. I receive answers for just category 1. It doesn't calculate values for Cat 2. when cat is mentioned as 2 in data. Still it compute and send result for 1 alone. — Sulthan, Feb 19 '17 at 12:29

How to solve: the condition has length > 1 and only the first element will be used

1 Answers1