[ncl-talk] Time Vs Lat/Lon
Adam Phillips
asphilli at ucar.edu
Thu Nov 1 09:42:52 MDT 2018
Hi Kunal,
In NCL v6.5.0 you can specify -4 as the 2nd option in cd_calendar. It
returns results that are the same as if you specify 0, so try specifying 0.
Again, you need to use dim_minind
<https://www.ncl.ucar.edu/Document/Functions/Contributed/dim_minind.shtml>
and dim_maxind
<https://www.ncl.ucar.edu/Document/Functions/Contributed/dim_maxind.shtml> to
return the index of the minimum (/maximum) value, and not dim_max/dim_min.
The latter two functions return the minimum and maximum values. You the
indices to plug them into your time array within the double do loop I sent
earlier.
Adam
On Thu, Nov 1, 2018 at 12:31 AM Kunal Bali <kunal.bali9 at gmail.com> wrote:
> I tried this but not working
>
> arr = a->BCSMASS
> lat = a->lat
> lon = a->lon
>
> printVarSummary(arr)
> timeT = cd_calendar(arr&time,-4) [==> *getting a warning*:cd_calendar:
> Unknown option, defaulting to 0.]
> time = timeT(:,3)
>
> ;arr_min = dim_min( arr(lat|:, lon|:, time|:) )
> ;printVarSummary(arr_min)
> ;printMinMax(arr_min,0)
>
> ;arr_max = dim_max( arr(lat|:, lon|:, time|:) )
> ;printVarSummary(arr_max)
> ;printMinMax(arr_max,0)
>
> ;time_min = arr_min ; arr_min contains the indices that were the
> minimum at each lat/lon point
> ;time_max = arr_max
> ;printVarSummary(time_max)
> do gg = 0,dimsizes(arr_min&lat)-1
> do hh = 0,dimsizes(arr_min&lon)-1
> time_min(gg,hh) = time(arr_min(gg,hh))
> time_max(gg,hh) = time(arr_max(gg,hh))
> end do
> end do
>
> ---
> Kunal Bali
>
>
>
>
>
>
>
> On Thu, Nov 1, 2018 at 3:05 AM Adam Phillips <asphilli at ucar.edu> wrote:
>
>> Hi Kunal,
>> Note that I recommended using dim_minind/dim_maxind, and not
>> minind/maxind. Looking at the file you attached, you would pass your
>> BCSMASS array into those two functions, and operate on the time (0)
>> dimension. As previously stated, that will return a 2D array dimensioned
>> lat x lon containing the desired indices. Then you would apply the double
>> do loop coding I sent to form arrays of the times themselves. Again, the
>> time array in my example coding needs to be set to something that is easily
>> plotted, say the Hour. You can set up an hour array for your data like this:
>> a = addfile("hourmean.nc","r")
>> arr = a->BCSMASS
>> timeT = cd_calendar(arr&time,-4)
>> time = timeT(:,3)
>>
>> Adam
>>
>> On Tue, Oct 30, 2018 at 12:02 PM Kunal Bali <kunal.bali9 at gmail.com>
>> wrote:
>>
>>> Thanks for this informations.
>>>
>>> I tried to get min mad max by using the link which you mentioned, but
>>> the error comes with fatal:Argument type mismatch on argument (0) of
>>> (maxind) can not coerce
>>>
>>> I also tried the code given below but facing the same error here.
>>> (version-NCL 6.4.0)
>>>
>>> dims = *dimsizes* <https://www.ncl.ucar.edu/Document/Functions/Built-in/dimsizes.shtml>(X)
>>> x1d = *ndtooned* <https://www.ncl.ucar.edu/Document/Functions/Built-in/ndtooned.shtml>(X) ; convert 2D array to 1D for use in maxind
>>> inds = *ind_resolve* <https://www.ncl.ucar.edu/Document/Functions/Built-in/ind_resolve.shtml>(*maxind* (x1d), dims) ; convert 1D array back to 2D
>>> ilat = inds(0,0) ; select the latitude index where the X array is at its' maximum
>>> ilon = inds(0,1) ; select the longitude index where the X array is at its' maximum
>>> lat_max = X&lat(ilat) ; insert the latitude index into the lat coordinate variable
>>> lon_max = X&lon(ilon) ; insert the longitude index into the lon coordinate variable
>>> *print* <https://www.ncl.ucar.edu/Document/Functions/Built-in/print.shtml>("Maximum value located at "+lat_max+", "+lon_max)
>>>
>>> I also attached one sample file, in case if you need it.
>>>
>>>
>>> ---
>>> Kunal Bali
>>>
>>>
>>>
>>>
>>>
>>>
>>> On Tue, Oct 30, 2018 at 2:47 AM Adam Phillips <asphilli at ucar.edu> wrote:
>>>
>>>> Hi Kunal,
>>>> If I understand correctly what you are after, you'd like to plot the
>>>> time (at each grid point) where the maximum (or minimum) value occurs.
>>>> This will likely take some trial and error on your part. Here's what I
>>>> think you need to do:
>>>> 1) Use dim_minind and dim_maxind to isolate the index where the grid
>>>> point value is at its min/max.
>>>> https://www.ncl.ucar.edu/Document/Functions/Contributed/dim_maxind.shtml
>>>> https://www.ncl.ucar.edu/Document/Functions/Contributed/dim_minind.shtml
>>>>
>>>> This will result in a 2-D array (dimensioned lat x lon) containing the
>>>> minimum indices, and the same type of array containing the maximum indices.
>>>>
>>>> 2) There might be a more elegant way to map the indexes onto the
>>>> correct times, but the following double do loop over the lat/lon dimensions
>>>> will work:
>>>>
>>>> ; time is an array of your times
>>>> time_min = arr_min ; arr_min contains the indices that were the
>>>> minimum at each lat/lon point
>>>> time_max = arr_max
>>>> do gg = 0,dimsizes(arr_min&lat)-1
>>>> do hh = 0,dimsizes(arr_min&lon)-1
>>>> time_min(gg,hh) = time(arr_min(gg,hh))
>>>> time_max(gg,hh) = time(arr_max(gg,hh))
>>>> end do
>>>> end do
>>>>
>>>> You will want to make sure that your time array is in a format that is
>>>> conducive to being plotted. (18:30 doesn't work for instance, but 1830
>>>> would.)
>>>> I think that's it. Try starting with the above suggestions and see if
>>>> you can get things to work. If you have further questions about this
>>>> subject please reply to the ncl-talk email list.
>>>> Adam
>>>>
>>>>
>>>>
>>>> On Mon, Oct 29, 2018 at 6:57 AM Kunal Bali <kunal.bali9 at gmail.com>
>>>> wrote:
>>>>
>>>>> Dear NCL users,
>>>>>
>>>>> I have one file (2000-2017) with time, latitude, longitude and
>>>>> variable. The time is given in hours(00:30 to 18:30). I need to plot a
>>>>> spatial map of hours values at each grid cells, the contour map of hours
>>>>> values should correspond to the variable values. So that I can see which
>>>>> hour has high and low-value on the map. Some examples are given for time vs
>>>>> latitude and time vs longitude, I don't need that. I need to plot time vs
>>>>> latitude longitude.
>>>>>
>>>>> I hope you got my point.
>>>>> Any information on that?
>>>>>
>>>>> Thank You
>>>>> ---
>>>>> Kunal Bali
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> ncl-talk mailing list
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>>>>>
>>>>
>>>>
>>>> --
>>>> Adam Phillips
>>>> Associate Scientist, Climate and Global Dynamics Laboratory, NCAR
>>>> www.cgd.ucar.edu/staff/asphilli/ 303-497-1726
>>>>
>>>> <http://www.cgd.ucar.edu/staff/asphilli>
>>>>
>>> _______________________________________________
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>>>
>>
>>
>> --
>> Adam Phillips
>> Associate Scientist, Climate and Global Dynamics Laboratory, NCAR
>> www.cgd.ucar.edu/staff/asphilli/ 303-497-1726
>>
>> <http://www.cgd.ucar.edu/staff/asphilli>
>>
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--
Adam Phillips
Associate Scientist, Climate and Global Dynamics Laboratory, NCAR
www.cgd.ucar.edu/staff/asphilli/ 303-497-1726
<http://www.cgd.ucar.edu/staff/asphilli>
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