Re: Possible bug in ncl 6.1.2 when accessing part of character array ?

Jatin,

You didn't show how you were converting the string in the V6.0.0 script. The "0x00" character you're seeing is the end-of-string character.

Let me back up a bit and explain these string conversion functions.

There are now four "convert from string to character" functions:

  tochar
  tocharacter (this one is unadvertised)
  stringtochar
  stringtocharacter

The "char" and "character" variations should behave identically to each other. That is, "tochar" is simply an alias for "tocharacter" and "stringtochar" is an alias for "stringtocharacter".

The behavior of tochar should be that *no* end-of-string character is returned, and with stringtochar, there is an end-of-string returned.

This is partly due for backwards incompatibility, and for giving the user two options of what is returned.

So, if you have the string "abcde". this is what you should see:

(0) -------------------------------------
(0) version = 6.1.2
(0) string = 'abcde'
(0) ----------tochar(a)-------------
(0) a
(1) b
(2) c
(3) d
(4) e
(0) ----------tocharacter(a)--------------
(0) a
(1) b
(2) c
(3) d
(4) e
(0) ----------stringtocharacter(a)--------------
(0) a
(1) b
(2) c
(3) d
(4) e
(5) 0x00
(0) ----------stringtochar(a)--------------
(0) a
(1) b
(2) c
(3) d
(4) e
(5) 0x00
(0) -------------------------------------

Note that "tochar" was not behaving correctly in versions 6.1.0 and earlier. I see that we didn't include this in our release notes, and I apologize for this. I'll try to remedy this shortly.

The documentation for these routines do reflect the differences you see in the behavior:

http://www.ncl.ucar.edu/Document/Functions/Built-in/tochar.shtml
http://www.ncl.ucar.edu/Document/Functions/Built-in/stringtochar.shtml

--Mary

On Nov 17, 2013, at 11:32 PM, Jatin Kala <jatin.kala.jk@gmail.com> wrote:

> Ok, in ncl 6.0.0, the character array has size 12:
>
> NCAR Command Language Version 6.0.0
> The use of this software is governed by a License Agreement.
> See http://www.ncl.ucar.edu/ for more details.
>
>
> Variable: some_char
> Type: character
> Total Size: 12 bytes
> 12 values
> Number of Dimensions: 1
> Dimensions and sizes: [12]
> Coordinates:
> (0) a
> (1) b
> (2) c
> (3) _
> (4) d
> (5) e
> (6) f
> (7) _
> (8) g
> (9) h
> (10) i
> (11) 0x00
>
> In NCL 6.1.2, the extra (0x00) is no longer there, and the size is 11:
> 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.
>
>
> Variable: some_char
> Type: character
> Total Size: 11 bytes
> 11 values
> Number of Dimensions: 1
> Dimensions and sizes: [11]
> Coordinates:
> (0) a
> (1) b
> (2) c
> (3) _
> (4) d
> (5) e
> (6) f
> (7) _
> (8) g
> (9) h
> (10) i
>
>
> That's why my code blew-up…… I just assumed that something as fundamental as the size of an array, irrespective of type, would always be the same, across NCL versions…. I guess this has something to do with the change of characters in NCL from signed to unsigned bytes or something?
>
> Cheers,
> Jatin.
>
>
>
>
>
> On 18/11/2013, at 4:50 PM, Jatin Kala wrote:
>
>> Hi NCL developers,
>> I think there is a bug in ncl/6.1.2. I am simply accessing part of a character array, and i get a different answer if i use 6.1.2 as compared to 6.0.0. Can others please confirm if they can re-produce this (or it's just me).
>>
>> Code:
>> some_char= tochar("abc_def_ghi")
>> print(some_char(dimsizes(some_char)-4:dimsizes(some_char)-2))
>>
>> Outputs:
>> [z3381484@monsoon Soil-Albedo-Scripts]$ which ncl
>> /share/apps/ncl/6.0.0/bin/ncl
>> [z3381484@monsoon Soil-Albedo-Scripts]$ ncl test_char.ncl
>> Copyright (C) 1995-2011 - All Rights Reserved
>> University Corporation for Atmospheric Research
>> NCAR Command Language Version 6.0.0
>> The use of this software is governed by a License Agreement.
>> See http://www.ncl.ucar.edu/ for more details.
>>
>>
>> Variable: some_char (subsection)
>> Type: character
>> Total Size: 3 bytes
>> 3 values
>> Number of Dimensions: 1
>> Dimensions and sizes: [3]
>> Coordinates:
>> (0) g
>> (1) h
>> (2) i
>> [z3381484@monsoon Soil-Albedo-Scripts]$ module remove ncl
>> [z3381484@monsoon Soil-Albedo-Scripts]$ module load ncl/6.1.2
>> [z3381484@monsoon Soil-Albedo-Scripts]$ which ncl
>> /share/apps/ncl/6.1.2/bin/ncl
>> [z3381484@monsoon Soil-Albedo-Scripts]$ ncl test_char.ncl
>> 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.
>>
>>
>> Variable: some_char (subsection)
>> Type: character
>> Total Size: 3 bytes
>> 3 values
>> Number of Dimensions: 1
>> Dimensions and sizes: [3]
>> Coordinates:
>> (0) _
>> (1) g
>> (2) h
>>
>>
>>
>>
>>
>
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Received on Mon Nov 18 08:37:15 2013