# [ncl-talk] Fewer questions about a Histogram Plot

Barry Lynn barry.h.lynn at gmail.com
Tue Nov 21 07:08:17 MST 2017

```Mary:

Thank you for the suggestions yesterday.  The histogram looks okay now.

I'd like to bring to your attention a couple of things.

1) I believe that the examples you have on the site do not necessarily (as
is) plot histograms typically drawn in meteorological papers. For instance,
when I originally tried to just plot the data in mod_x and obs_x using the
standard examples it didn't work.  For this reason, I created intervals of
data whose index is the interval value and the number of times the index
value appears is equal the value of the data (obs_x or obs_y) within.

For instance, if there is an interval with 10001 grids with dBZ values
(radar reflectivity) within this interval then that index will have 10001
values, all equal to the value of the index.

2) I do this with this loop and am wondering if there is an more concise
way to write it.

i_num = 0

i_end = 0

i_beg = 0

do i_int = 0,dims_obs_x-1

i_end = i_beg + floattointeger(obs_x(i_int))

do x_int = i_beg,i_end-1

x_new(i_num) = i_int

i_num = i_num + 1

end do

if (i_beg.eq.i_end)then

x_new(i_num) = i_int

i_num = i_num + 1

end if

i_beg = i_end

end do

3) If I take your program and substitute my data (num_x) at the top I get
the strange figure attached (00002.png).  We're I to put this data into a
typical graphing program, the data would come out correctly as
histo_mod.pdf.

Perhaps I've overlooked something?

Thanks,

Barry

On Mon, Nov 20, 2017 at 7:19 PM, Mary Haley <haley at ucar.edu> wrote:

> Barry,
>
> You don't want to use discrete bin intervals, unless you are wanting to
> count the # of values *exactly equal* to a value.
>
> For a range of values, use gsnHistogramBinIntervals.
>
> Please read over the histogram page carefully, because we have many
>
> As I think I mentioned before, I updated example histo_2.ncl to show how
> to explicitly request an array of bin intervals.
>
> Run the attached script, will hopefully illustrate the difference between
> gsnHistogramBinIntervals and gsnHistogramDiscreteBinValues.
>
> --Mary
>
>
> On Mon, Nov 20, 2017 at 8:54 AM, Barry Lynn <barry.h.lynn at gmail.com>
> wrote:
>
>> Hello:
>>
>> I found the coding lines that allows me to map the number of intervals,
>> explicitly.  I found the coding lines that allow me to specify how many of
>> the labels I want to map.
>>
>> That's here:
>>
>> https://www.ncl.ucar.edu/Applications/Scripts/histo_3.ncl
>>
>>  res at tmXBLabelStride                = 2     ; every other x-label
>>   res at gsnHistogramDiscreteBinValues  = ispan(0,25,1)
>>
>> However, I don't see how to change the number of labels to be different
>> from their default number, which equals the number of tmXBValues.
>>
>> I need to set the latter so that I can add more than 9 labels.
>>
>> Thank you
>>
>>
>> (0) res at tmXBLabels = -9
>>
>> (1) res at tmXBLabels = 0
>>
>> (2) res at tmXBLabels = 9
>>
>> (3) res at tmXBLabels = 18
>>
>> (4) res at tmXBLabels = 27
>>
>> (5) res at tmXBLabels = 36
>>
>> (6) res at tmXBLabels = 45
>>
>> (7) res at tmXBLabels = 54
>>
>> (8) res at tmXBLabels = 63
>>
>> (0) tmXBValues = 0.0555556
>>
>> (1) tmXBValues = 0.166667
>>
>> (2) tmXBValues = 0.277778
>>
>> (3) tmXBValues = 0.388889
>>
>> (4) tmXBValues = 0.5
>>
>> (5) tmXBValues = 0.611111
>>
>> (6) tmXBValues = 0.722222
>>
>> (7) tmXBValues = 0.833333
>>
>> (8) tmXBValues = 0.944444
>>
>> On Mon, Nov 20, 2017 at 3:01 PM, Barry Lynn <barry.h.lynn at gmail.com>
>> wrote:
>>
>>> Hi:
>>>
>>> I can get the labels to display correctly if I use:
>>>
>>> res at tmXBLabels = int_radar(::3)
>>>
>>>
>>> However, the histogram program is amalgamating the smaller bins into 10
>>> sized default bins.
>>>
>>>
>>> I would hope that there is a way to explicitly tell the histogram
>>> program to use all the interval data (23 intervals.
>>>
>>>
>>> I tried setting:
>>>
>>>
>>> res at tmXBMode        = "Manual"
>>>
>>> and creating manual tick marks, but then my histogram labels go only
>>> from 0 to 1.
>>>
>>>
>>> As below.
>>>
>>>
>>>
>>>
>>>
>>>   new_ticks(0)= 0
>>>
>>>
>>>
>>>   end do
>>>
>>>   print("new_ticks = " + new_ticks)
>>>
>>>   res at tmXBValues := new_ticks
>>>
>>>   res at tmXBLabels := int_radar
>>>
>>> On Sun, Nov 19, 2017 at 9:21 PM, Barry Lynn <barry.h.lynn at gmail.com>
>>> wrote:
>>>
>>>> Hi:
>>>>
>>>> I am having trouble figuring out why my histo.ncl program won't plot
>>>> data beyond value (x-axis) of 15.  This is really dbz data, so the range is
>>>> correct: -9 to 60.
>>>>
>>>> I also checked that the labels are present in:
>>>>
>>>> res at tmXBLabels = int_radar
>>>>
>>>>
>>>> and the data dimensions are correct (23 elements).
>>>>
>>>> However, I don't see any data (and any labels 18-60) indicating that
>>>> the data has all been displayed.
>>>>
>>>> Thank you,
>>>>
>>>> Barry
>>>>
>>>> --
>>>> Barry H. Lynn, Ph.D
>>>> Senior 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
>>>> US 914 432 3108 <(914)%20432-3108>
>>>>
>>>
>>>
>>>
>>> --
>>> Barry H. Lynn, Ph.D
>>> Senior 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
>>> US 914 432 3108 <(914)%20432-3108>
>>>
>>
>>
>>
>> --
>> Barry H. Lynn, Ph.D
>> Senior 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
>> US 914 432 3108 <(914)%20432-3108>
>>
>> _______________________________________________
>> 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 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
US 914 432 3108
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