Skip to content

Can anyone help why the errors are coming and rectify it?

7 messages · Sri krishna Devarayalu Balanagu, Duncan Murdoch, (Ted Harding) +3 more

Duncan Murdoch
#
On 12-09-17 5:47 AM, Sri krishna Devarayalu Balanagu wrote:
The lines above are two complete statements.
The "else" is not allowed to start a statement.  You need to make sure 
the "if" is incomplete when you start the line containing else.  The 
usual style is

if (cond) {
   stmt1

# The if is still incomplete, because the closing brace is missing

} else {

# now the else will be accepted

   stmt2
}

Duncan Murdoch
(Ted Harding)
#
On 17-Sep-2012 09:47:41 Sri krishna Devarayalu Balanagu wrote:
Reformatting your code (for readability) but preserving your
line breaks:

  invalid.ids <- c(1,3,5)
  if (length(invalid.ids)==0) {
    cat("No Errors found")
  }
  else {
    cat(paste(invalid.ids), sep="\n")
  } }

  Error: unexpected 'else' in "else"
  Error: unexpected '}' in "        }"

First:

The first four lines are a completed command, given the way
that R parses input. After encountering the end-of-line at
the fourth line, R considers that it has seen a complete command
and therefore executes it.

 invalid.ids <- c(1,3,5)
  if (length(invalid.ids)==0) {
    cat("No Errors found")
  }

Therefore the "else {" on the next line is not interpreted as
if it were part of the preceding "if()" statement, since that
has been considered complete and has been executed. So that
"else" is an "else" with no matching "if". Henc the the first
error message.

Second: if you count the opening "{" and closing "}", you will
see that there is one "}" too many, at the end, hence the second
error message.

The way to avoid the first error message is to put the "else"
on the same line as the close of the "if" statement. Then R will
recognise that it has an incomplete commend, and continue to parse
further input until it has built up a complete command. So you
should write:

  invalid.ids <- c(1,3,5)
  if (length(invalid.ids)==0) {
    cat("No Errors found")
  } else {
    cat(paste(invalid.ids), sep="\n")
  }

(Note that the extra "}" has been omitted too).

Hoping this helps,
Ted.


-------------------------------------------------
E-Mail: (Ted Harding) <Ted.Harding at wlandres.net>
Date: 17-Sep-2012  Time: 12:29:46
This message was sent by XFMail
R. Michael Weylandt
# 
And now it is easy to see why we should all the one true brace style ;-)

Michael
On Mon, Sep 17, 2012 at 12:29 PM, Ted Harding <Ted.Harding at wlandres.net> wrote:
Jessica Streicher
# 
Now i know why using else never worked for me - really, i'd consider this more of a bug than a feature of the language ;)
On 17.09.2012, at 14:35, R. Michael Weylandt wrote:

            

      
      
      
    

        

      
      
    

            

      
      
      
    

        

      
      
    

  
  


  


      

    

    

      
      

        


  

        

      R. Michael Weylandt
    

    

      
      #
    

  


  

      
On Mon, Sep 17, 2012 at 2:54 PM, Jessica Streicher

        
<j.streicher at micromata.de> wrote:

            

      
      
      
    

        
If it makes you feel any better (I can't imagine it would), javascript
has the same 'feature' for much the same reason.  Python doesn't, but
then again, they don't have braces so the parsing is easier (i.e.,
there exist universalizable rules)....

Michael

            

      
      
      
    

  
  


  


      

    

    

      
      

        


  

        

      Patrick Burns
    

    

      
      #
    

  


  

      
This is Circle 8.1.43 of 'The R Inferno'.

http://www.burns-stat.com/pages/Tutor/R_inferno.pdf

Pat

        
On 17/09/2012 10:47, Sri krishna Devarayalu Balanagu wrote: