[ncl-talk] Computing max of monthly NO2 data each year

Wed Sep 30 09:27:47 MDT 2015

Attached is a script with many 'print' and 'printVarSummary' statements.
You should carefully examine each output.

Deeply embedded 'do loops' should always be examined to see if array
syntax or functions should/could be used. This is particularly true of
interpreted languages.

You should read about 'coordinate subscripting', 'named dimensions', etc.

Under 'Support', click 'Manuals'

A Mini-Language reference manual explains some NCL features.

The Mini-Graphics is a bit out of date BUT the DKRZ Tutorials should
be helpful for you.

See attached

On Tue, Sep 29, 2015 at 2:37 PM, Thierno <thiernodoumbia at yahoo.fr> wrote:
> Thank Alan,
> Your script is very helpfull for me.
>
> Thierno
>
> Envoyé de mon iPhone
>
> Le 29 sept. 2015 à 21:18, Alan Brammer <abrammer at albany.edu> a écrit :
>
> Looks like You got things sorted with Jack pretty well.
>
> I went through and cleaned up your code a little, to make it a little more
> concise in my opinion.  Functionally it will be the same, but if you go
> through and understand my changes here it may help you in the future.
>
> f1 = "Europe_bis_ncl.txt"
>
> EU     = readAsciiTable(f1,7,"float",1)
> EU at _FillValue = -9999
> EU!0 = "time"
> EU!1 = "variable"
> ;; if the dimeensions are named they can be reordered very easily.
>
> ;************************************************
> ; to plot multiple lines, you must put them into
> ; a mulidimensional array
> ;************************************************
>
> nraw = 8
> ncol = 276
> nmax = ncol/12
>
> EU_plot      = new((/nraw,ncol/),float, EU at _FillValue)
> EU_plot(:6,:) = EU(variable|:, time|120:395)  ; name the dimensions and
> reorder easily.
> EU_plot(7,:) = dim_avg_n(EU_plot(0:6,:),0)
>
> EUmax := new((/nraw,nmax/),float, EU_plot at _FillValue)
>
>
> ;; rather than having 3 different iterable integers, simplify things with an
> array up front.
> ;;;;
> t_lbd = ispan(0, ncol-12, 12)   ;  lower bounds to find max over.
> t_ubd = t_lbd + 11              ;  upper bounds to find max over.
>
>
> do t=0,dimsizes(t_lbd)-1
>   EUmax(:,t) = dim_max_n(EU_plot(:,t_lbd(t):t_ubd(t)),1)   ;; use the array
> based functions where possible.
> end do
>
> print(EUmax)
>
>
>
>
> On Tue, Sep 29, 2015 at 12:22 PM, Doumbia <thiernodoumbia at yahoo.fr> wrote:
>>
>> I add some thing in your code and it gives me the good results.
>> yr = i would be yr = i+1.
>>
>> The new script is:
>> do n=0,7
>>     yr=0
>>     k =0
>>     do i = 11,275,12
>>        EUmax(n,k) = max(EU_plot(n,yr:i))
>>        k=k+1
>>        yr=i+1
>>     end do
>>  end do
>>
>> Jack, thank again.
>> Thierno
>>
>> > Le 29 Sep 2015 à 18:02, Doumbia <thiernodoumbia at yahoo.fr> a écrit :
>> >
>> > Hi Jack,
>> > I really appreciate your teaching skills.
>> >
>> > I recognize that there’s weird things in my script but I apologize for
>> > that, I am new in NCL.
>> >
>> > Unfortunately, your suggestions don’t give the good results i.e. the
>> > maximum of monthly NO2 data for each year. I compared these results with
>> > those obtained from excel.
>> >
>> > You are right, the "EU(120:395,0)” is for 1990 to 2012 (23 years).
>> >
>> > Thank you for your help.
>> >
>> > Thierno
>> >
>> >
>> >>
>> >> ...
>> >> “The results I’ve obtained aren’t what I expected.”
>> >> ...
>> >> Well, even Aristotle would struggle to figure out what you expected if
>> >> you didn't tell him…
>> >>
>> >> Your script still got visible mistakes though. For example the loop is
>> >> quite extravagant:
>> >> …
>> >> k = ispan(0,11,1)
>> >> do n=0,7
>> >>  do i = 0,275,12
>> >>   do j=0,11
>> >>     EUmax(n,:) = max(EU_plot(n,i+k(j))) <== “j” will always be the same
>> >> type as, and equal to “k(j)”?
>> >>   end do
>> >>  end do
>> >> end do
>> >> …
>> >> and since the left side of your equation has a free dimension, the
>> >> variable will always be overwritten up to the end of the loop.
>> >>
>> >> You can clean the loop and do something like,
>> >> do n=0,7
>> >>    yr=0
>> >>    k =0
>> >>    do i = 11,275,12
>> >>       EUmax(n,k) = max(EU_plot(n,yr:i))
>> >>       k=k+1
>> >>       yr=i
>> >>    end do
>> >> end do
>> >>
>> >> I was also wondering whether from your file “EU(120:395,0)” will give
>> >> you information from 2000 to 2012(12 years)? Probably that is the unexpected
>> >> result you mentioned. Who knows?
>> >>
>> >> I hope that helps.
>> >>
>> >> Jack
>> >>
>> >>> On 29 Sep 2015, at 15:02, Doumbia <thiernodoumbia at yahoo.fr> wrote:
>> >>>
>> >>> Dear ncl users,
>> >>>
>> >>> I am trying to compute the monthly maximum NO2 in a yearly basis.
>> >>>
>> >>> My input file contains 7 columns representing different variables and
>> >>> 396 lines (monthly mean NO2 data from 1980 to 2012). I am only interested by
>> >>> the 2000-2012 period .
>> >>>
>> >>> The results I’ve obtained aren’t what I expected.
>> >>> <max_of_monthly_data.ncl><Europe_bis_ncl.txt>
>> >>> I will appreciate any help to resolve this.
>> >>>
>> >>> Please find attached my script as well as my input file.
>> >>>
>> >>> Thank you in advance,
>> >>> Thierno
>> >>>
>> >>> _______________________________________________
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>> >>
>> >
>>
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>
>
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