Unexpected 'else' in "else" error

Question

I get this error:

Error: unexpected 'else' in " else"

From this if, else statement:

if (dsnt<0.05) {
     wilcox.test(distance[result=='nt'],distance[result=='t'],alternative=c("two.sided"),paired=TRUE) }
else {
      if (dst<0.05) {
wilcox.test(distance[result=='nt'],distance[result=='t'],alternative=c("two.sided"),paired=TRUE) }
   else {
         t.test(distance[result=='nt'],distance[result=='t'],alternative=c("two.sided"),paired=TRUE)       } }

What is wrong with this?

Drobman

Your if statement is complete by the second line. Move the curly bracket at the end of it to the start of the 3rd line. Do the same for the 5th. – Pallbearer

Possible duplicate of #13724563 – Vorfeld

Answer 1

You need to rearrange your curly brackets. Your first statement is complete, so R interprets it as such and produces syntax errors on the other lines. Your code should look like:

if (dsnt<0.05) {
  wilcox.test(distance[result=='nt'],distance[result=='t'],alternative=c("two.sided"),paired=TRUE)
} else if (dst<0.05) {
  wilcox.test(distance[result=='nt'],distance[result=='t'],alternative=c("two.sided"),paired=TRUE)
} else {
  t.test(distance[result=='nt'],distance[result=='t'],alternative=c("two.sided"),paired=TRUE)       
} 

To put it more simply, if you have:

if(condition == TRUE) x <- TRUE
else x <- FALSE

Then R reads the first line and because it is complete, runs that in its entirety. When it gets to the next line, it goes "Else? Else what?" because it is a completely new statement. To have R interpret the else as part of the preceding if statement, you must have curly brackets to tell R that you aren't yet finished:

if(condition == TRUE) {x <- TRUE
 } else {x <- FALSE}

Pallbearer

It's just odd that R requires this only when the if statement isn't inside a block. Inside of a block, you can write the else on its own and R will correctly associate it with the preceding if. Outside of a block, it won't. Weird. – Rochelle

You're right, but I don't think it's that weird. When in a block, R can look ahead and see what comes next because all instructions are given at once, whereas in line by line it doesn't have a way to look ahead to the next line. – Pallbearer

Answer 2

I would suggest to read up a bit on the syntax. See here.

if (dsnt<0.05) {
  wilcox.test(distance[result=='nt'],distance[result=='t'],alternative=c("two.sided"),paired=TRUE) 
} else if (dst<0.05) {
    wilcox.test(distance[result=='nt'],distance[result=='t'],alternative=c("two.sided"),paired=TRUE)
} else 
  t.test(distance[result=='nt'],distance[result=='t'],alternative=c("two.sided"),paired=TRUE)

Homonym

Just when I thought that I should add the rewritten code to be nice, I realized the answer already been answered by sebastian-c .. – Homonym

Sorry about that. I did appreciate the link to the language definition, though. It does answer the question. – Pallbearer

Answer 3

I dislike braces (too much python programming I guess). My solution for simple if else like

if(condition == TRUE) {x <- TRUE
 } else {x <- FALSE}

is

if(condition == TRUE) 
   x <- TRUE
else 
   x <- FALSE

is clear enough.

Towards

Me, too. But gives unexpected token else on my machine, and, if executed, Error: unexpected 'else' in "else". – Gonion

Answer 4

I just wanted to add that this doesn't happen if the if-else clauses are within a for-loop for some reason. You can have as many blank lines as you want between the end of the if-curly brackets and the else. I understand the explanation, but I find it extremely stupid that R doesn't just think "oh I thought the statement was complete, but since the next thing is 'else' I guess it's not," especially since that's apparently what it does in for-loops. So basically I can't style my code the way I like it in every case and have to change it depending on whether it's in a for-loop or not.

Magnifico