[ncl-talk] avoiding loops

[Dennis Shea]

 If array 'x' is (say) float, abd you do

   x = toint(x)   ; floattointeger(x)
   print(typeof(x))   ; float

the 'x' will still be float. NCL coerces to integer to float. Use the
reassignment operator  :=

  x *:=* toint(x)   ; use syntac := to reassign float to integer
  print(typeof(x))   ; integer

Then you can use the fortran integer  descriptors.


On Mon, Sep 23, 2019 at 1:32 PM Dave Allured - NOAA Affiliate via ncl-talk <
ncl-talk at ucar.edu> wrote:

> Fortran 90+ also has I0 format to suppress leading zeros on integers.  Use
> that with integer data for this application.
>
> Floattointeger will not convert to integer if you assign the result to a
> pre-existing float variable.  Try assigning the result to a new variable
> not previously defined, or a previously defined variable of type integer.
> Use printVarSummary to confirm.
>
> I think you could also use floattointeger in-line within the write_matrix
> procedure call, and save a little memory that way.
>
>
> On Mon, Sep 23, 2019 at 11:00 AM Micah Sklut <micahs2005 at gmail.com> wrote:
>
>> NCL wont allow me to use i5 format on the variable. I've used the
>> floattointeger, but when I print that variable, it still shows that is of
>> type float, even though the values were properly converted to integer.
>>
>> On Mon, Sep 23, 2019 at 12:57 PM Dennis Shea <shea at ucar.edu> wrote:
>>
>>> *  fmtf*
>>>
>>> Format to be used, specified *via Fortran style*. The format string
>>> used must agree with the variable type.
>>>
>>> ===
>>>
>>> Google fortran edit descriptors..
>>>
>>> "384(f0.1,','),f0.1"
>>>
>>> "384(i5,','),i5"
>>>
>>> On Mon, Sep 23, 2019 at 12:43 PM Micah Sklut via ncl-talk <
>>> ncl-talk at ucar.edu> wrote:
>>>
>>>> This worked great Dave. I appreciate the great support. I did the
>>>> asciiread to read back in all the string arrays, and then used write_table
>>>> to format the final output.
>>>>
>>>> One last question. When formating the write_matrix calls, I'm trying to
>>>> write a float variable to integer format.  When I use, floattointeger
>>>> function, it properly converts the values to integers, however, it doesn't
>>>> change the variable type in the metadata from float to integer. This
>>>> doesn't allow me to write_matrix using integer format. Is there an easy way
>>>> to get around this?
>>>>
>>>> On Sun, Sep 22, 2019 at 8:31 PM Dave Allured - NOAA Affiliate <
>>>> dave.allured at noaa.gov> wrote:
>>>>
>>>>> Write_matrix is strictly for output to only a text file, or Unix
>>>>> standard output.  There is no internal write capability.  However, you can
>>>>> simulate internal writes by using one or more temporary files.
>>>>>
>>>>> Read the formatted lines back in from a temp file with asciiread
>>>>> ("tmp.txt", -1, "string").  This gives you a 1-D array of strings, one full
>>>>> line for each of your grid points.  Then repeat for each of your other
>>>>> variables.  This will efficiently give you arrays of full formatted line
>>>>> strings for several variables.
>>>>>
>>>>> You should then be able to join these line strings together, however
>>>>> you have in mind.  Also, now that you are operating on strings, you can add
>>>>> text columns at the beginning or end of each string, if this would be of
>>>>> any help.  For example:
>>>>>
>>>>> long_lines = "precip," + p_lines(:) + ",Tmin," + tmin_lines(:) +
>>>>> ",Tmax," + tmax_lines(:)
>>>>>
>>>>> This example is for joining horizontally.  You could also join
>>>>> vertically by simply joining the string arrays, with or without
>>>>> interleaving.  There are many variations on this theme, depending on how
>>>>> you want your final output to be structured.
>>>>>
>>>>>
>>>>> On Sun, Sep 22, 2019 at 5:29 PM Micah Sklut <micahs2005 at gmail.com>
>>>>> wrote:
>>>>>
>>>>>> Instead of sending output to a file, is it possible to do a
>>>>>> write_matrix formatting to 1d array?  I need to add more than 1 of these
>>>>>> variables together, so if I can create 1d arrays for all of the variables
>>>>>> and metadata, such as lat/lon, then I can use write_table to join
>>>>>> everything together. When I'm re-ordering or reshaping the arrays, I'll
>>>>>> just need to delete the old arrays, to free up memory.
>>>>>>
>>>>>> On Sun, Sep 22, 2019 at 1:51 PM Dave Allured - NOAA Affiliate <
>>>>>> dave.allured at noaa.gov> wrote:
>>>>>>
>>>>>>> There is a mistake in the untested example that I sent.  Please
>>>>>>> change the format spec from "384(f0.1,','),f0.1" to "383(f0.1,','),f0.1".
>>>>>>> The latter is correct for 384 numbers per line.  I split the format spec
>>>>>>> into two parts so that there would not be a trailing comma at the end of
>>>>>>> each line.
>>>>>>>
>>>>>>> Generally speaking, the format spec in write_matrix is specified for
>>>>>>> a single output line.  It is repeated for each output line.  It is
>>>>>>> important that the total item count in the format spec (383 + 1 in this
>>>>>>> case) exactly matches the intended number of items per line.
>>>>>>>
>>>>>>>
>>>>>>> On Sun, Sep 22, 2019 at 11:32 AM Micah Sklut <micahs2005 at gmail.com>
>>>>>>> wrote:
>>>>>>>
>>>>>>>> Okay, thanks, Dave.  That sounds like what I need. I've always
>>>>>>>> struggled with the formatting in NCL, but I'll give that a go and see where
>>>>>>>> I get.
>>>>>>>>
>>>>>>>> On Sun, Sep 22, 2019 at 1:26 PM Dave Allured - NOAA Affiliate <
>>>>>>>> dave.allured at noaa.gov> wrote:
>>>>>>>>
>>>>>>>>> Try write_matrix and the F0 format descriptor.  F0 format is part
>>>>>>>>> of fortran 90 and up.  It is described in modern fortran documentation.  It
>>>>>>>>> is like the common Fw.d format descriptor, except leading blanks to the
>>>>>>>>> left of the decimal point are suppressed.
>>>>>>>>>
>>>>>>>>> Reshape your array from, e.g. (lat,lon,time), to a 2-D array in
>>>>>>>>> the desired output order, (points,time).  Npoints = Nlats x Nlons.  Then a
>>>>>>>>> single call to write_matrix should write the entire output file:
>>>>>>>>>
>>>>>>>>>     opt = True
>>>>>>>>>     opt at fout = "temperature.csv"
>>>>>>>>>     write_matrix (data_out, "384(f0.1,','),f0.1", opt)
>>>>>>>>>
>>>>>>>>> You can add arbitrary extra numeric columns to the output array,
>>>>>>>>> if it would be helpful to have lats and lons, or other such metadata, on
>>>>>>>>> each line of output.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> On Sat, Sep 21, 2019 at 2:53 PM Micah Sklut via ncl-talk <
>>>>>>>>> ncl-talk at ucar.edu> wrote:
>>>>>>>>>
>>>>>>>>>> Hi,
>>>>>>>>>>
>>>>>>>>>> I have a task to take GFS data and concatenate variables across
>>>>>>>>>> all the forecast hours, for each grid point.
>>>>>>>>>>
>>>>>>>>>> For example, taking a temperature variable for each grid point,
>>>>>>>>>> for all latitude and longitudes, and creating a string that represents the
>>>>>>>>>> values for each forecast hour.
>>>>>>>>>> So, if we have for latitude y, and longitude x, there would be a
>>>>>>>>>> string value like "70.5,71.5,71.5,72.0,...nHours".  The end product will be
>>>>>>>>>> a line for each grid point for the variables i"m looking at that will be
>>>>>>>>>> written to a file to be imported into a database.
>>>>>>>>>>
>>>>>>>>>> Creating loops through all hours, latitudes, and longitudes will
>>>>>>>>>> get the job done, but is expensive and was looking to see if there were any
>>>>>>>>>> NCL functions that would help here.
>>>>>>>>>>
>>>>>>>>>> Thank you.
>>>>>>>>>>
>>>>>>>>> _______________________________________________
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