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Re: Chained-functional notation examples?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg132705] Re: Chained-functional notation examples?
  • From: "Hans Michel" <hmichel at cox.net>
  • Date: Fri, 9 May 2014 02:06:47 -0400 (EDT)
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  • References: <zLEb1n00r1r5Uyi01LEcLm> <000901cf6ac8$b3fb5470$1bf1fd50$@cox.net> <zScg1n0170owH2401SchCY>

I think the dates would have to be rounded to Day then the AbsoluteTime
would be more comparable.

AbsoluteTime[DayRound[DateList[], All]] < 
 AbsoluteTime[DayRound[DayPlus[DateList[], 3], All]]

Issues may be file dates compared to current date time, rounding and
location (timezone) issues.

DayRound is New in version 9
Switch to Take[] goes all the back to v1. AbsoluteTime v2.

AbsoluteTime[Take[DateList[], 3]] < 
 AbsoluteTime[Take[DayPlus[DateList[], 3], 3]]

FileDate[] in the original suggestion by Daniel only goes back to v3.

To address the poster's original  questions: I don't believe that
Mathematica has issues in filtering or using a water-fall like method. I
can't speak to if Mathematica optimizes such a process.

Hans
-----Original Message-----
From: Daniel Lichtblau [mailto:danl at wolfram.com] 
Sent: Thursday, May 08, 2014 9:37 AM
To: Hans Michel; mathgroup at smc.vnet.net
Subject: [mg132705] Re: Chained-functional notation examples?


On 05/08/2014 09:20 AM, Hans Michel wrote:
> Daniel:
>
> Now What's the catch with Today?
>
> Today will only work in Wolfram Language (Mathematica v 10), which may 
> be officially released Tomorrow?
>
> One can go on with a Who's on First theme. (Goes along with W|A 
> baseball
> data)
>
> But currently the DateObject "Today" would have to be changed to 
> something that would work in Mathematica 9 or below.
>
> Hans

Hans et al,

You are correct, I was using an unreleased version. Actually some good came
of it (I found a weakness in date comparisons that got addressed).
I'll leave modification for versions <=9 to others more adept at this sort
of thing. I never was much good with dates...

As for baseball,

http://www.redreporter.com/2012/2/13/2796324/hus-on-first-a-modernization

Daniel


> -----Original Message-----
> From: Daniel Lichtblau [mailto:danl at wolfram.com]
> Sent: Thursday, May 08, 2014 3:08 AM
> To: mathgroup at smc.vnet.net
> Subject: Re: Chained-functional notation examples?
>
>
> A query such as this might do what you have in mind. Here 
> directoryname should be changed to whatever directory you want searched.
>
> Select[FileNames[("*uid*" | "*UID*"), directoryname, Infinity],
>       ((StringMatchQ[DirectoryName[#] , "*egal*"] && Today < 
> DayPlus[FileDate[#], 3]) &]
>
> Also there is a case sensitive switch if you want to allow strings with
e.g.
> "uID". If you want to allow that uid only in the name and not full 
> string
>
> Daniel Lichtblau
> Wolfram Research
>
> -------------------
>
> On Tue, 06 May 2014 06:26:46 +0000, Unknown wrote:
>
>   > I came to 'Mathematica' via Xahlee's criticism of the ad-hoc 
> nature of  > unix-piping [functional notation].  He claims [& I 
> believe him] that  > Mathematica has a better, more consistent 
> notation.  But the facility of  > PRE, IN & POST-fix alternatives, 
> seems bad.  You want ONE way of  > acieving the goal. More rules just
increases mental load.
>   >
>   > A major benefit of functional [unix-piping] programming style, is 
> that  > you don't need to remember the-full-journey: you just need to 
> remember  > the previous stage's output. Nor do you need to remember
several names:
>   > the previous output is just "it".  A superficial read through a 
> recent  > article[s] here, about <collecting data from several 
> servers, and  > agregating it, and sending the result to a master> 
> seemed very  > interesting, and matches my ideas of using functional 
> programming.  But  > I can't afford to invest in ANOTHER 
> notation/syntax, without good  > prospect of productivety increase.
>   >
>   > Just as a test, how would Mathematica handle the following [or 
> part of]
>> little task:
>   >
>   > search all files in Dir=tree D |
>   >  which are less than N days-old |
>   >  and which contain string S1 |
>   >  and which contain string S2 .
>   >
>   > Actually, this seems not a good example, since it's biased towards 
> the  > *nix file system's format/syntax.
>   >
>   > Try:
>   > Search in table of ListOfOpenFiles for lineS with path-P [field] |  
> > which have same tty-field as line with path-P2 & program-M [field]  
> >  > This sounds like a data-base problem?
>   >
>   > Or is there a nice list of 'such' Mathematica examples?
>   >
>   >  Thanks,
>   >
>   > == John Grant.
>
> Here's a related real-live problem:
>    list all files in Dir-tree:D |
>    which are less-than daysOld:N |
>    and contain "egal" in the FullPathName |
>     and contain String:"uid" OR "UID"
>




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