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Date:         Sun, 4 Feb 2007 09:57:37 -0500
Reply-To:     Wensui Liu <liuwensui@GMAIL.COM>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         Wensui Liu <liuwensui@GMAIL.COM>
Subject:      Re: why infile much faster than proc import
Comments: To: Peter Crawford <>
In-Reply-To:  <>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

good summary, Peter! I totally agree with you that syntax of data step is more intuitive than proc import in this case.

On 2/4/07, Peter Crawford <> wrote: > On Sat, 3 Feb 2007 14:34:42 -0500, Wensui Liu <liuwensui@GMAIL.COM> wrote: > > >I just did a speed comparison of csv file import between infile and > >proc import and realized infile is much much ... ... faster. > > > >what's the trick behind it? > > > >thanks. > >-- > >WenSui Liu > >A lousy statistician who happens to know a little programming > >( > > > WenSui Liu > > I'm not surprised with the results you reported. > > I know this may not be in mainstream thinking, but I would only use > proc import for a preliminary look at column structure of a file. > Even then, I would only do that for an input file of unknown origins. > > Generally we know where a file has come from and what it's structure > should be. So, generally, I would use a datastep infile statement to > connect the process with the data, and input statements to parse the > data. And I can expect to be precise in my definition and results. > That is something proc import cannot match when reading plain text, > because it does not know the information structure, so it has to try > to discover what columns are present in the input file. > > If we want to import from something that is not plain text, why use > proc import? Instead we can use the relevant SAS library engine to > deliver the data directly. Under the covers the excel engine > gemerates syntax that looks like some flavour of sql. > > Proc import will never satisfy my need to be specific and precise > about parsing input text. The data step provides all the > flexibility and control for handling text in complex structure. > For simple structure, data step syntax is probably easier to learn > than proc import ( but thats just my opinion) > > Peter Crawford > Crawford Software Consultancy >

-- WenSui Liu A lousy statistician who happens to know a little programming (

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