On Fri, Jan 1, 2010 at 3:03 PM, jim holtman <jholt...@gmail.com> wrote:
> ?try
>
> df <- try(read.table(...))
> if (inherits(df, 'try-error')){ what to do if file empty }
For the case of using try, it is better to use inherits() rather than
class(), or it doesn't matter?
> On Fri, Jan 1, 2010 at 3:55 PM, Ted Harding <ted.hard...@manchester.ac.uk>
> wrote:
>>
>> On 01-Jan-10 20:41:52, Peng Yu wrote:
>> > read.table terminates the program if the input file is empty. Is there
>> > way to let the program continue and return me a NULL instead of
>> > terminating the program?
>> >
>> > $ Rscript read_empty.R
>> >> read.table("empty_data.txt")
>> > Error in read.table("empty_data.txt") : no lines available in input
>> > Execution halted
>> > $ cat read_empty.R
>> > read.table("empty_data.txt")
>> > $ cat empty_data.txt; echo EOF
>> > EOF
>>
>> If I understand the point of your query correctly, the following,
>> from "?read.table", would be relevant:
>>
>> Value:
>> A data frame (?data.frame?) containing a representation of the
>> data in the file.
>>
>> Empty input is an error unless "col.names" is specified, when a
>> 0-row data frame is returned: similarly giving just a header line
>> if "header = TRUE" results in a 0-row data frame. Note that in
>> either case the columns will logical unless ?colClasses? was
>> supplied.
>>
>> The result would not be NULL, but can be tested for zero rows.
>>
>> Hoping this helps,
>> Ted.
>>
>> --------------------------------------------------------------------
>> E-Mail: (Ted Harding) <ted.hard...@manchester.ac.uk>
>> Fax-to-email: +44 (0)870 094 0861
>> Date: 01-Jan-10 Time: 20:55:35
>> ------------------------------ XFMail ------------------------------
>>
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>
>
>
> --
> Jim Holtman
> Cincinnati, OH
> +1 513 646 9390
>
> What is the problem that you are trying to solve?
>
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