Skip to content

No "number of days" format for 'difftime'?

9 messages · Rui Barradas, John Kane, Loris Bennett +1 more

Original
Loris Bennett
# 
Hi,

When I try

  d <- as.difftime("6-08:18:33",format=%d-%H:%M:%S")

I get:

  Error: unexpected SPECIAL in "as.difftime("6-08:18:33",format=%d-%"

Am I correct in thinking that it is not possible to do something like
this, because there is no character string for the format which
corresponds to "number of days"?

I could misuse "%j" for "day of the year as a decimal number", but
ultimately the "difftime" object is still a data, rather than a length
of time and I should be looking at a package like 'lubridate' instead.
Is that the case?

Cheers,

Loris
John Kane
# 
Try 
d <- as.difftime("6-08:18:33","%d-%H:%M:%S")

John Kane
Kingston ON Canada
____________________________________________________________
Can't remember your password? Do you need a strong and secure password?
Use Password manager! It stores your passwords & protects your account.
Rui Barradas
# 
Hello,

You're missing a double quotes. Right after format=

Hope this helps,

Rui Barradas
?

Citando Loris Bennett <loris.bennett at fu-berlin.de>:
?
Loris Bennett
# 
Hi,

I was probably misled by the, to my mind, esoteric error message into
thinking the error was more subtle.  Something like "unmatched quotes"
might have helped me recognise that I was just being dopey.

Thanks to John and Rui.

Loris

<ruipbarradas at sapo.pt> writes:

  
    

      
      
    

  


  


      

    

    

      
      

        


  

        

      John Kane
    

    

      
      #
    

  


  

      
http://www.dummies.com/how-to/content/how-to-read-errors and-warnings-in-r.html
If something goes wrong with your code, R tells you. We have to admit it: These error messages can range from mildly confusing to completely incomprehensible if you?re not used to them.


fortune(350) regarding the on-line help is also inspiring

You need to get the hang of reading the online help. The information required is actually therein ?dotchart --- it's just tersely and obscurely expressed. A certain degree of optimism is required. You need to ***believe*** that the information is there; then ask yourself "What could they possibly mean by what they have written that would tell me what I need to know?".
   -- Rolf Turner (on reading the help pages)
      R-help (June 2013)


John Kane
Kingston ON Canada

            

      
      
      
    

        

      
      
    

            

      
      
      
    

        

      
      
    

            

      
      
      
    

        

      
      
    

        
____________________________________________________________
FREE 3D MARINE AQUARIUM SCREENSAVER - Watch dolphins, sharks & orcas on your desktop!

  
  


  


      

    

    

      
      

        


  

        

      Loris Bennett
    

    

      
      #
    

  


  

      
Thanks for the link, John.  However, there is a hyphen missing.  It
should be:

  http://www.dummies.com/how-to/content/how-to-read-errors-and-warnings-in-r.html

Appropriately, with the correct URL we find the too often forgotten
pearl of wisdom:

 "Chances are, you just typed something wrong there."

I think I need this on my coffee cup.

Cheers,

Loris


John Kane <jrkrideau at inbox.com> writes:

            

      
      
      
    

        

      
      
    

            

      
      
      
    

        

      
      
    

            

      
      
      
    

        

      
      
    

            

      
      
      
    

        

      
      
    

        

  
    

      
      
    

  


  


      

    

    

      
      

        


  

        

      Loris Bennett
    

    

      
      #
    

  


  

      
Loris Bennett <loris.bennett at fu-berlin.de> writes:

            

      
      
      
    

        
Continuing the topic for my future self and others equally poorly versed
in The Art and Dark Science of Interpreting R Error Messages, if I have
the following in the file "my_data"

1094165      2016-07-24T09:40:02 13-23:03:28          1  COMPLETED 
1112076      2016-08-01T14:45:49 6-13:26:15          1  COMPLETED 

and do

            

      
      
      
    

        
I get the following:

Error in as.difftime(elapsed, format = "%d-%H:%M:%S") : 
  'tim' is not character or numeric

Remembering that if something is not what you think it is, it is
probably a factor, I find that

            

      
      
      
    

        
causes the error to go away.

So what's all this 'tim' business?  A quick squint at the source code of
datetime.R reveals the following line:

  if (!is.numeric(tim)) stop("'tim' is not character or numeric")

So the error message tells me something about the arbitrary name of the
variable 'tim', which could also have been 'tom', 'dick', or 'harriet',
but nothing about the value.

So follow Rolf Turner's fortune(350) advice, then look at the source
code, and then realise that you weren't being totally dopey in not
understanding the error message.

Loris

  
    

      
      
    

  


  


      

    

    

      
      

        


  

        

      Martin Maechler
    

    

      
      #
    

  


  

          

      
      
      
    

        
> Loris Bennett <loris.bennett at fu-berlin.de> writes:
    >> Thanks for the link, John.  However, there is a hyphen missing.  It
    >> should be:
    >> 
    >> http://www.dummies.com/how-to/content/how-to-read-errors-and-warnings-in-r.html
    >> 
    >> Appropriately, with the correct URL we find the too often forgotten
    >> pearl of wisdom:
    >> 
    >> "Chances are, you just typed something wrong there."
    >> 
    >> I think I need this on my coffee cup.
    >> 
    >> Cheers,
    >> 
    >> Loris

    > Continuing the topic for my future self and others equally poorly versed
    > in The Art and Dark Science of Interpreting R Error Messages, if I have
    > the following in the file "my_data"

    > 1094165      2016-07-24T09:40:02 13-23:03:28          1  COMPLETED 
    > 1112076      2016-08-01T14:45:49 6-13:26:15          1  COMPLETED 

    > and do

    >> d <- read.table("my_data")
    >> colnames(d) <- c("jobid","start","elapsed","alloccpus","state")
    >> df <- transform(d,start = as.POSIXct(start,format="%Y-%m-%dT%H:%M:%S"),elapsed = as.difftime(elapsed,format="%d-%H:%M:%S"))

    > I get the following:

    > Error in as.difftime(elapsed, format = "%d-%H:%M:%S") : 
    > 'tim' is not character or numeric

Well, let me argue that you should have found this to be a *helpful*
error message. You are no complete beginner anymore, right,
so

1) the error is in your use of  as.difftime().

2) ?as.difftime  or  str(difftime)
   both clearly indicate that  'tim' is the first argument of as.difftime,

and I really do wonder why you continued with the infamous
"trial-and-error programming technique" instead of reading or at
least quickly browsing the relevant reference, i.e., help page

Martin


    > Remembering that if something is not what you think it is, it is
    > probably a factor, I find that

    >> d <- read.table(data_file,stringsAsFactors=FALSE)

    > causes the error to go away.

    > So what's all this 'tim' business?  A quick squint at the source code of
    > datetime.R reveals the following line:

    > if (!is.numeric(tim)) stop("'tim' is not character or numeric")

    > So the error message tells me something about the arbitrary name of the
    > variable 'tim', which could also have been 'tom', 'dick', or 'harriet',
    > but nothing about the value.

    > So follow Rolf Turner's fortune(350) advice, then look at the source
    > code, and then realise that you weren't being totally dopey in not
    > understanding the error message.


    > Loris

    > -- 
    > Dr. Loris Bennett (Mr.)
    > ZEDAT, Freie Universit?t Berlin         Email loris.bennett at fu-berlin.de

  
  


  


      

    

    

      
      

        


  

        

      Loris Bennett
    

    

      
      #
    

  


  

      
Martin Maechler <maechler at stat.math.ethz.ch> writes:

            

      
      
      
    

        
My apologies, you are absolutely right - I see the error of my ways.
The only feeble defence I can mount is that the usage example from
?as.difftime

  as.difftime(tim, format = "%X", units = "auto")

superficially disguises the fact that the first argument is also a named
argument with the name 'tim'.  I think I had assumed that the initial
argument were always positional, e.g. as for paste0

  paste0(..., collapse = NULL)

However, I now realise that '...' also generates named arguments, e.g.

  paste0(..1='a',..2='b')

So as a non-beginner but infrequent R user, in future I shall try use
the explicit form more often, e.g.

  as.difftime(tim = "4-03:02:01", format = "%d-%H:%M:%S")

to remind myself what I am doing.

So fortune(350) really is true.  I just didn't believe enough to read
enough. 

Loris