Re: Chained-functional notation examples?

*To*: mathgroup at smc.vnet.net*Subject*: [mg132709] Re: Chained-functional notation examples?*From*: Bill Rowe <readnews at sbcglobal.net>*Date*: Fri, 9 May 2014 02:08:07 -0400 (EDT)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*Delivered-to*: l-mathgroup@wolfram.com*Delivered-to*: mathgroup-outx@smc.vnet.net*Delivered-to*: mathgroup-newsendx@smc.vnet.net

On 5/7/14 at 2:44 AM, dog at gmail.com (Unknown) wrote: >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" It is not entirely clear what it is you are trying to do. There are a couple of ways to obtain a list of files in a given directory. First, if the directory is the current working directory, then FileName[] will return a list of every thing at the top level of the directory. But in this case, only the name of things at that level are returned not the path name. If the directory is a subdirectory of the current working directory you can get a list of files in that directory with FileNames["*", dirname] This will return a relative path name, relative to the current working directory. If you want the full path name then using the last form above with dirname specified with the full path name will give you what you want. I will assume the desired files are in the current working directory and you want any file with "egal" in the path name at any sub directory level with those assumptions the problem above can be solved as: Cases[ Flatten@StringCases[ FileNames["*",Directory[],Infinity],___~~"egal"~~___], _?( FileType[#]===File && Subtract@@(AbsoluteTime/@{Date[][[;;3]],FileDate[#][[;;3]]}/86400)>age && FindList[#,{"UID","uid"}]!={} &)] The FileType portion filters out directories, the Subtract@@ portion computes the age of the file in days and compares that to a specified age and the FindLIst portion looks to see if the file contains either "UID" or "uid". Cases checks each file for the three conditions above and only returns a those that meet all three conditions. Note, while this isn't a difficult thing to do in Mathematica, if all you need to do is solve this class of problem, i.e., something were you need a list of files meeting a specified criteria, Mathematica really is overkill and an expensive way to solve this class of problem. What Mathematica can do with files is all kinds of sophisticated numerical analysis on the file contents, analysis that could be very time consuming to implement in something such as Perl, Python etc. It makes sense to solve this class of problem within Mathematica when you already have a license to Mathematica, are familiar with Mathematica and solving this problem is merely a subset of a larger problem. But it definitely does not make sense to me to buy a license for Mathematica for just the ability to locate files in this manner. There are far less expensive solutions for this problem. Another thing to consider. I've been using Mathematica since version 1.2 and pretty much on a daily basis since version 3.0. I consider myself quite proficient using Mathematica to solve problems I encounter. But despite using Mathematica extensively for quite a number of years, I do not see myself as fully mastering Mathematica. And the level of proficiency I have achieved was not achieved in a few days or a few weeks. Mathematica is extremely versatile and is a very rich toolset for solving a large variety of programs. But that versatility comes at a price. Mathematica has what I would consider a rather steep learning curve to climb before proficiency is achieved.

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