topic Re: how many records in the raw data in SAS Programming

how many records in the raw data

GeorgeSAS — Wed, 22 Jun 2016 13:50:23 GMT

Hello,

I want use data step to read a very large raw data with infile statement.

firstly I want to know how many rows in the file,if I only want to read the last records, I can use firstobs=n obs=n option but I need to know the value of n first.

Please help.

DATA read_last_obs;
INFILE raw1 FIRSTOBS=9999999 OBS=9999999.;
INPUT a $50.;
RUN;

Thanks!

Re: how many records in the raw data

RW9 — Wed, 22 Jun 2016 13:59:31 GMT

I don't think so, reading in a text file is a linear process, its starts at character 1 and runs to the end of the file. Why can you not proces the data once its read in, even really big files shouldn't take that long? Why would you want only a few observations from the end?

Re: how many records in the raw data

LinusH — Wed, 22 Jun 2016 13:59:48 GMT

Take a look at the END= INFILE option.

Re: how many records in the raw data

Astounding — Wed, 22 Jun 2016 14:30:47 GMT

If you are working under Linux/Unix this can be done. But the exact statements are beyond my Unix knowledge. Here's the idea.

Unix contains a "tail" command that lists end of a file. Instead of listing it, the results can be piped to a file.

Now combine all of this with an INFILE statement. The INFILE statements contains the "tail" command, piping its results as part of the INFILE statement definition (rather than to a file). The combination lets the INFILE statement retrieve the tail end of the data source.

If you indicate that this would be useful for you, I'm sure someone on the board can give you more specific code.

Re: how many records in the raw data

GeorgeSAS — Wed, 22 Jun 2016 14:49:58 GMT

I just want to get last row of record, this will save time and space if i know the total number of rows

Thanks!

Re: how many records in the raw data

Astounding — Wed, 22 Jun 2016 20:01:45 GMT

Found a Unix command to count number of lines in a file:

wc -l filename

Are you working on Unix?

Re: how many records in the raw data

GeorgeSAS — Thu, 23 Jun 2016 02:04:05 GMT

working on z/os

Thanks

Re: how many records in the raw data

Ksharp — Thu, 23 Jun 2016 02:57:20 GMT

 DATA _null_;
  INFILE '/folders/myfolders/all_jd.csv' end=last;
  INPUT;
  n+1;
  if last then putlog 'NOTE: File have ' n ' rows.'/
                      'The last row is:' _infile_ ;
  RUN;

Re: how many records in the raw data

GeorgeSAS — Fri, 08 Jul 2016 13:23:25 GMT

Thank you Ksharp,
But your method need to read the whole raw file first, then counting the obs, while I don't want to read the whole file because time cost a lot!
Thanks!

Re: how many records in the raw data

Ksharp — Sat, 09 Jul 2016 03:03:32 GMT

Maybe you should take a look at the function relate to FILE,
Like FGET(), FOPEN() .............

But I totally don't have any clue about it .