Re: Issue with isfilepresent (NCL version 6.1.2)

Hi Dave,

Thanks for your thoughts on this. The isfilepresent is one of those functions we wish we could have a “do over” on.

We’ve added your comments to our ticket on this, NCL-1852. We plan to address these issues in NCL V6.2.1 (no scheduled date yet), and will document the behavior in the appropriate locations.

—Mary

On May 22, 2014, at 12:35 PM, Dave Allured - NOAA Affiliate <dave.allured@noaa.gov> wrote:

> NCL support team,
>
> Thank you for introducing the upcoming fileexists function, this is much needed.
>
> Here are some more suggestions to reduce ongoing confusion with the old isfilepresent function.
>
> Consider deprecating the function under the name isfilepresent. Replace it with a new name that clearly indicates it is for supported file formats, not general file system queries. Something like "issupportedfile".
>
> At the same time, please revise the existing documentation for isfilepresent as well as for the proposed new function. Please indicate clearly:
>
> 1. issupportedfile and isfilepresent are for testing for supported addfile formats, NOT general file presence.
>
> 2. Two conditions must be satisfied to return True. The named file must exist on the file system, and it must be one of the addfile supported formats.
>
> 3. The functions return False when a file is present with the given name, but is not one of the addfile supported formats. This is a restatement of (3) to try to make the behavior extremely clear. I think this needs to be stated explicitly.
>
> 4. Please include a hyperlink to documentation for addfile supported formats.
>
> 5. Please indicate that in some cases, isfilepresent and issupportedfile will also check for files with alternate file name extensions. Please include information or a link on how alternate names are determined by NCL.
>
> 6. Please include a cross-referencing note that fileexists should be used for general file name testing, for supported files as well as all other possible file types.
>
> Thanks for your consideration.
>
> --Dave
>
> On Tue, May 20, 2014 at 9:28 AM, Wei Huang <huangwei@ucar.edu> wrote:
> Saji,
>
> There are some issues with "isfilepresent(xxx)" in 6.2.0, and earlier versions.
>
> The original idea of "isfilepresent(xxx)" is to check if file "xxx" can be handled by NCL.
> If NCL can read (more specifically with NetCDF, HDF, HDFEOS),
> then "isfilepresent(xxx)" should return True, otherwise it returns False.
> But sometimes, users, even the developers, may misunderstand this function, and misuse it.
>
> To clear the above, we are introducing a new function: "fileexists(xxx)".
> Which will be just like a Unix command to check if file "xxx" exists.
> And "isfilepresent(xxx)" will check if file "xxx" can be handled/read by NCL.
>
> In your example:
>
> print(fileexists("../test")) will be True
> print(fileexists("../test2")) will be False.
>
> and
>
> print(isfilepresent("../test")) and print(isfilepresent("../test2") will both return False.
> As a side effects, since NCL will do a lot of checks on these two case,
> where the first case will cause some error message, and the second one cause
> a lot of error message.
>
> Unfortunately, all these changes will be in 6.2.1 release later.
>
> If you want the most recent NCL executable (beyond 6.2.0), please let us know.
>
> If you have any concerns/suggestions regarding this issue, please feedback to ncl-talk.
>
> Thanks,
>
> Wei
>
> On May 15, 2014, at 7:47 PM, Saji Hameed <saji.nh@gmail.com> wrote:
>
>> Dear NCL developers.
>>
>> The return value from isfilepresent is wrong when using relative paths. In my
>> case I am trying to see if a certain file is present in the parent directory, for e.g
>> isfilepresent.
>>
>> An example
>>
>> $ touch ../test
>>
>> Copyright (C) 1995-2013 - All Rights Reserved
>> University Corporation for Atmospheric Research
>> NCAR Command Language Version 6.1.2
>> The use of this software is governed by a License Agreement.
>> See http://www.ncl.ucar.edu/ for more details.
>> ncl 0> print(isfilepresent("../test"))
>> (0) True
>> ncl 1> print(isfilepresent("../test2"))
>> (0) True
>> ncl 2> exit
>>
>> The file "../test2" does not really exist. The following from the linux command line
>> returns the correct answers.
>>
>> $ test -f ../test ; echo $?
>> 0
>>
>> $ test -f ../test2 ; echo $?
>> 1
>>
>> The function isfilepresent returns correct answers if I use the full path.
>>
>> Here are the NCL and system details
>>
>> NCL version 6.1.2
>>
>> $ uname -a
>> Linux enformtk 2.6.32-41-server #90-Ubuntu SMP Tue May 22 12:41:40 UTC 2012 x86_64 GNU/Linux
>>
>>
>> saji
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>
>
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Received on Fri May 23 15:32:20 2014