[gradsusr] SET A CONSTANT

Stephen McMillan smcmillan at planalytics.com
Thu Mar 21 13:43:12 EDT 2019


Sorry, I had some superfluous comments in my last.  Stephen

On Thu, Mar 21, 2019 at 1:41 PM Stephen McMillan <smcmillan at planalytics.com>
wrote:

> Arlindo,
>
> I have found if_() is particularly useful when any part of the field is
> undefined (-u), since if() will not work with undefined values.  That is
> well documented in http://cola.gmu.edu/grads/gadoc/gradfuncif.html.
>
> I will use if() when I can but will continue to use if_() when undefined
> is involved, as is frequently the case.  Thanks for keeping that function
> in opengrads.
>
> Stephen Mc
>
> where dt has values >= 0 along with missing values (-u)
>
> So, it appears that undefined grid values must be changed to a "defined"
> value representing an undefined value, before one can use the if function
> on such fields.
>
> Inter
>
> On Wed, Mar 20, 2019 at 11:38 PM Arlindo da Silva <dasilva at alum.mit.edu>
> wrote:
>
>> On Fri, Mar 15, 2019 at 9:14 AM Stephen McMillan <
>> smcmillan at planalytics.com> wrote:
>>
>>> Marian,
>>> You are correct, regarding the "if" function in your version of
>>> OpenGrADS.  The syntax I provided was for the latest (2.2.1) version.  In
>>> the latest OpenGrADS version, you can either use "if" with the syntax as I
>>> provided, or use "if_" with the syntax you provided.  Either way, you're
>>> good to go!
>>>
>>>
>> This is a subtle point. OpenGrADS has included an if() function for many
>> years. Recently, COLA introduced an if() function, but unfortunately with a
>> different syntax so it broke the code of people that had been using the
>> OpenGrADS version. In 2.2.1 I renamed the OpenGrADS version if_() so they
>> two can co-exist, although I strongly recommend that everyone migrate to
>> the COLA version.
>>
>>    Arlindo
>>
>>
>>
>>
>>
>>> Best wishes--
>>> Stephen
>>>
>>> On Thu, Mar 14, 2019 at 10:53 PM AMS EmsiWx Bytča <
>>> emsiwx at pocasie-bytca.sk> wrote:
>>>
>>>> Once again thank you both guys, gave up const/maskout after sveral
>>>> hours combining :D , used IF (did not know that it is already in 2.1.x
>>>> version which I have), the correct syntax is:
>>>>
>>>>
>>>> 'define A=if(tempdif,>,25,0,if(tempdif,>=,22,2,6))'
>>>>
>>>>
>>>> Marian
>>>>
>>>>
>>>>
>>>> Dňa 14. 3. 2019 o 20:04 AMS EmsiWx Bytča napísal(a):
>>>>
>>>> Thank you Jeff and Stephen, will try to play with const/maskout first,
>>>> then I will reinstall my Opengrads and try the if statement.
>>>>
>>>>
>>>> Marian
>>>> Dňa 14. 3. 2019 o 15:09 Stephen McMillan napísal(a):
>>>>
>>>> Marian,
>>>>
>>>> One correction to what I sent...
>>>>
>>>> 'define A=if(dt>25,0,if(dt>=22,2,6))'     added the second )
>>>>
>>>> Stephen
>>>>
>>>> On Thu, Mar 14, 2019 at 10:06 AM Stephen McMillan <
>>>> smcmillan at planalytics.com> wrote:
>>>>
>>>>> Marian,
>>>>>
>>>>> If you have the latest version of GrADS or OpenGrADS, you could do
>>>>> something like this:
>>>>>
>>>>> 'define dt=t850-t500'
>>>>> 'define A=if(dt>25,0,if(dt>=22,2,6)'
>>>>> 'd A'
>>>>>
>>>>> Stephen McMillan
>>>>>
>>>>> On Wed, Mar 13, 2019 at 4:14 PM AMS EmsiWx Bytča <
>>>>> emsiwx at pocasie-bytca.sk> wrote:
>>>>>
>>>>>> Dear all,
>>>>>>
>>>>>>
>>>>>> I am going crazy combining const/maskout to get what I need.
>>>>>>
>>>>>> I need to set A according the following:
>>>>>>
>>>>>> A= 0 when T850-T500 >25
>>>>>>
>>>>>> A= 2 when T850-T500 22-25
>>>>>>
>>>>>> A= 6 when T850-T500 <22
>>>>>>
>>>>>>
>>>>>> Would like to ask any master of const/maskout for help.
>>>>>>
>>>>>>
>>>>>> Thank you very much in advance.
>>>>>>
>>>>>>
>>>>>> Marian
>>>>>>
>>>>>> _______________________________________________
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>>>>>> http://gradsusr.org/mailman/listinfo/gradsusr
>>>>>>
>>>>>
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>>
>>
>> --
>> Arlindo da Silva
>> *dasilva at alum.mit.edu <dasilva at alum.mit.edu>*
>> _______________________________________________
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>>
>

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