# [ncl-talk] Wondering why I am getting this dimensions error

Barry Lynn barry.h.lynn at gmail.com
Wed Nov 27 12:37:23 MST 2019

```Hi Rashed:

I have a two dimensional array.  It is all zeroes.

I set it equal to a "where" statement, where I add + 1 in every grid point
where the "where" condition is satisfied.

The 2d array now has 0s and 1s.  If I were to use the where statement
again, i.e., for another k level, without setting the 2d array to 0, first,
then it would now have 0s, 1, and 2s.

I thought that I could do the addition and get a 1 D sum, by setting a 1 d
array = to the where statement.  That's not possible.

I have to sum the 2d array to get a single 1 d array....

I hope that clears things up. If not, I can answer you off line.

Barry

On Wed, Nov 27, 2019 at 9:31 PM Rashed Mahmood <rashidcomsis at gmail.com>
wrote:

> Hi Barry,
> Obviously, you know what you are doing. However, I still can't get it.
> What do you mean by "it should become an array of just 0s and 1s" and most
> importantly how could it become an array of 0's and 1s?
> Anyway, you can ignore this message, if nothing more to discuss.
>
> On Wed, Nov 27, 2019 at 11:20 AM Barry Lynn <barry.h.lynn at gmail.com>
> wrote:
>
>> Hi:
>>
>> Normally, it would be a sum of 2s and 1s, but because I am only doing the
>> sum once (for each k), it should becomes an array of  just 0's and  1s.
>>
>> Originally, I thought if I set a 1 D array equal to the where statement,
>> it would sum the 2d array.  To do that, I had to actually sum it (add_q).
>>
>> Barry
>>
>> On Wed, Nov 27, 2019 at 8:58 PM Rashed Mahmood <rashidcomsis at gmail.com>
>> wrote:
>>
>>> Sorry for chipping in here, and may be I am wrong but I do not follow
>>> the logic:
>>>
>>> If you do: sum_q :=  where(qs(k,:,:).ge.0.1,sum_q+1,sum_q)
>>>
>>> The variable "sum_q" would be a 2d array containing *2s* and *1s*. Do
>>> you want a sum of 2s and 1s or you want a sum of qs(k,:,:) where it is
>>> greater than 0.1?
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> On Wed, Nov 27, 2019 at 10:50 AM Barry Lynn via ncl-talk <
>>> ncl-talk at ucar.edu> wrote:
>>>
>>>> Hi:
>>>>
>>>> The problem with the previous suggestion was that the sum_q became a 2
>>>> dimensional variable..  I needed it to be a 1D variables. I found this out
>>>> by using the "function" printVarSummary
>>>>
>>>> Here is the correct solution for my needs, based on the very helpful
>>>>
>>>> Thanks
>>>>
>>>> (sum_q was defined as a 2d variable -- note: sum_q is not really a sum,
>>>> as used here, but defined as 1 whereever qs > 0.1).
>>>>
>>>>        sum_q = 0
>>>>
>>>>        sum_q(0,0) = 1 ; just so I don't divide by 0!
>>>>
>>>>        sum_q =  where(qs(k,:,:).ge.0.1,sum_q+1,sum_q)
>>>>
>>>>        add_q = sum(sum_q); a 1d variable
>>>>
>>>>  ;      printVarSummary(qs_1(k))
>>>>
>>>>   ;     printVarSummary(sum_q)
>>>>
>>>>
>>>>
>>>> On Wed, Nov 27, 2019 at 8:18 PM Dennis Shea <shea at ucar.edu> wrote:
>>>>
>>>>> re:   :=
>>>>> Yes.
>>>>>
>>>>> On Wed, Nov 27, 2019 at 10:49 AM Barry Lynn via ncl-talk <
>>>>> ncl-talk at ucar.edu> wrote:
>>>>>
>>>>>> Hi Dave:
>>>>>>
>>>>>> Thank you for your suggestions.
>>>>>>
>>>>>> I actually need to sum_q for all elements of the remaining (:,:) 2d
>>>>>> array to obtain a single number.
>>>>>>
>>>>>> I am dividing one number by it.
>>>>>>
>>>>>> I assume that it is okay to put the := and that I will get the sum
>>>>>> over all 2d elements?
>>>>>>
>>>>>> On Wed, Nov 27, 2019 at 7:40 PM Dave Allured - NOAA Affiliate <
>>>>>> dave.allured at noaa.gov> wrote:
>>>>>>
>>>>>>> "sum_q = 1." defines this variable as scalar.  Then the where
>>>>>>> statement attempts to write a 2-D array onto a scalar.  The assignment
>>>>>>> statement is not allowed to change dimensions.
>>>>>>>
>>>>>>> One way to fix this would be to use the reassignment operator ":=",
>>>>>>> which IS allowed to change dimensions on assignment.
>>>>>>>
>>>>>>> Another way to fix this would be to define sum_q as a 2-D array
>>>>>>> before the start of the loop.  I suspect that is what you really intended.
>>>>>>>
>>>>>>>
>>>>>>> On Wed, Nov 27, 2019 at 10:22 AM Barry Lynn via ncl-talk <
>>>>>>> ncl-talk at ucar.edu> wrote:
>>>>>>>
>>>>>>>> Hi:
>>>>>>>>
>>>>>>>> I have some simple code.
>>>>>>>>
>>>>>>>>       do k = 0,dims3d(0)-1
>>>>>>>>
>>>>>>>>        qs(k,:,:) = where(qs(k,:,:).lt.0.1,q_null(k,:,:),qs(k,:,:))
>>>>>>>>
>>>>>>>>        sum_q = 1.
>>>>>>>>
>>>>>>>>        sum_q =  where(qs(k,:,:).ge.0.1,sum_q+1,sum_q)
>>>>>>>>
>>>>>>>>        qs_1(k) = sum(qs(k,:,:))/sum_q+qs_1(k)
>>>>>>>>
>>>>>>>>       end do
>>>>>>>>
>>>>>>>>
>>>>>>>> Why can't I do the "where" sum?
>>>>>>>>
>>>>>>>>
>>>>>>>> fatal:Number of dimensions on right hand side do not match number
>>>>>>>> of dimension in left hand side
>>>>>>>>
>>>>>>>> --
>>>>>>>> Barry H. Lynn, Ph.D
>>>>>>>> Senior Associate Scientist, Lecturer,
>>>>>>>> The Institute of the Earth Science,
>>>>>>>> The Hebrew University of Jerusalem,
>>>>>>>> Givat Ram, Jerusalem 91904, Israel
>>>>>>>> Tel: 972 547 231 170
>>>>>>>> Fax: (972)-25662581
>>>>>>>>
>>>>>>>> C.E.O, Weather It Is, LTD
>>>>>>>> Weather and Climate Focus
>>>>>>>> http://weather-it-is.com
>>>>>>>> Jerusalem, Israel
>>>>>>>> Local: 02 930 9525
>>>>>>>> Cell: 054 7 231 170
>>>>>>>> Int-IS: x972 2 930 9525
>>>>>>>>
>>>>>>>
>>>>>>
>>>>>> --
>>>>>> Barry H. Lynn, Ph.D
>>>>>> Senior Associate Scientist, Lecturer,
>>>>>> The Institute of the Earth Science,
>>>>>> The Hebrew University of Jerusalem,
>>>>>> Givat Ram, Jerusalem 91904, Israel
>>>>>> Tel: 972 547 231 170
>>>>>> Fax: (972)-25662581
>>>>>>
>>>>>> C.E.O, Weather It Is, LTD
>>>>>> Weather and Climate Focus
>>>>>> http://weather-it-is.com
>>>>>> Jerusalem, Israel
>>>>>> Local: 02 930 9525
>>>>>> Cell: 054 7 231 170
>>>>>> Int-IS: x972 2 930 9525
>>>>>>
>>>>>> _______________________________________________
>>>>>> ncl-talk mailing list
>>>>>> ncl-talk at ucar.edu
>>>>>> List instructions, subscriber options, unsubscribe:
>>>>>> http://mailman.ucar.edu/mailman/listinfo/ncl-talk
>>>>>
>>>>>
>>>>
>>>> --
>>>> Barry H. Lynn, Ph.D
>>>> Senior Associate Scientist, Lecturer,
>>>> The Institute of the Earth Science,
>>>> The Hebrew University of Jerusalem,
>>>> Givat Ram, Jerusalem 91904, Israel
>>>> Tel: 972 547 231 170
>>>> Fax: (972)-25662581
>>>>
>>>> C.E.O, Weather It Is, LTD
>>>> Weather and Climate Focus
>>>> http://weather-it-is.com
>>>> Jerusalem, Israel
>>>> Local: 02 930 9525
>>>> Cell: 054 7 231 170
>>>> Int-IS: x972 2 930 9525
>>>>
>>>> _______________________________________________
>>>> ncl-talk mailing list
>>>> ncl-talk at ucar.edu
>>>> List instructions, subscriber options, unsubscribe:
>>>> http://mailman.ucar.edu/mailman/listinfo/ncl-talk
>>>
>>>
>>
>> --
>> Barry H. Lynn, Ph.D
>> Senior Associate Scientist, Lecturer,
>> The Institute of the Earth Science,
>> The Hebrew University of Jerusalem,
>> Givat Ram, Jerusalem 91904, Israel
>> Tel: 972 547 231 170
>> Fax: (972)-25662581
>>
>> C.E.O, Weather It Is, LTD
>> Weather and Climate Focus
>> http://weather-it-is.com
>> Jerusalem, Israel
>> Local: 02 930 9525
>> Cell: 054 7 231 170
>> Int-IS: x972 2 930 9525
>>
>>

--
Barry H. Lynn, Ph.D
Senior Associate Scientist, Lecturer,
The Institute of the Earth Science,
The Hebrew University of Jerusalem,
Givat Ram, Jerusalem 91904, Israel
Tel: 972 547 231 170
Fax: (972)-25662581

C.E.O, Weather It Is, LTD
Weather and Climate Focus
http://weather-it-is.com
Jerusalem, Israel
Local: 02 930 9525
Cell: 054 7 231 170
Int-IS: x972 2 930 9525
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