[ncl-talk] Bar Graph/Histogram plot question

Barry Lynn barry.h.lynn at gmail.com
Tue Apr 25 11:14:03 MDT 2017


Hi:

I have been using example 6.

However, the page says: "Compares two arrays. Both arrays are combined into
a single array with the first dimension equal to 2,"

and implies that both arrays are of the same length.

In my case, they are of different lengths.

Regarding the bar graphs -- I didn't see this particular page when I first
looked for bar graphs.  However, it won't be helpful if I can't put one
behind the other (and slightly off to the side) like you can with
res at gsnHistogramCompare        = True

Barry

On Tue, Apr 25, 2017 at 7:06 PM, Mary Haley <haley at ucar.edu> wrote:

> Hi Barry,
>
> Those numbers at the top are coming from this line, which sets the main
> title for your plot:
>
>   res at tiMainString = str_join(""+x,",")
>
> Remove or comment this line.
>
> In what way do you want to combine the two graphs?  Do you want the bars
> side-by-side, or stacked?
>
> As an example, visit this page:
>
> http://www.ncl.ucar.edu/Applications/bar.shtml
>
> and look at:
>
> unique_5.ncl
> bar_10.ncl
> bar_15.ncl
>
> etc
>
> You can also look at the histogram page, see histo_6.ncl:
>
> http://www.ncl.ucar.edu/Applications/histo.shtml#ex6
>
> --Mary
>
>
> On Tue, Apr 25, 2017 at 9:46 AM, Barry Lynn <barry.h.lynn at gmail.com>
> wrote:
>
>> Hi:
>>
>> I followed Mary's comments to imply that the histogram function plots the
>> number of elements within each interval.  Hence, when my obs distribution
>> show, for example 227, I created 227 consecutive elements with the value 0,
>> and then proceeded through the distribution.
>>
>> I would like to do the following:
>>
>> 1) remove the list of numbers at the top of each graph,
>>
>> 2) Combine the graphs.
>>
>> The typical approach doesn't work (bottom of code) because there are
>> different numbers of x and y.
>>
>> Thank you for your suggestions.
>>
>> Barry
>> P.S. The code runs stand alone.
>>
>> On Tue, Apr 25, 2017 at 12:34 AM, Mary Haley <haley at ucar.edu> wrote:
>>
>>> Hi Barry,
>>>
>>> The gsn_histogram function takes whatever "bin" values you give it, and
>>> counts the number of values that fall in each bin, and then draws this as a
>>> bar.
>>>
>>> If you don't provide any bins, then gsn_histogram will pick "nice" bins
>>> for you.
>>>
>>> The binning happens such that no values are binned in more than one
>>> interval.
>>>
>>> Try running the attached script.
>>>
>>> In the first plot, I let gsn_histogram pick the bin intervals.
>>>
>>> The first bin, which is from 1 to 2, will capture all values >= 1 and <
>>> 2, the second bin counts all values >=2 and < 3 and so on.  The very last
>>> bin, 9 to 10, will count all values >= 9 and <= 10.
>>>
>>> The second plot I specifically set the bin intervals that I want.
>>>
>>> In the third plot, instead of counting values that fall in a range, I
>>> set an array of discrete values to explicitly count.
>>>
>>> Hope this helps clear things up.
>>>
>>> --Mary
>>>
>>>
>>> On Sun, Apr 23, 2017 at 2:23 AM, Barry Lynn <barry.h.lynn at gmail.com>
>>> wrote:
>>>
>>>> Hi:
>>>>
>>>> I have data specified as below.
>>>>
>>>> I adapted code from this page:
>>>>
>>>> https://www.ncl.ucar.edu/Applications/histo.shtml
>>>>
>>>> Example # 6.
>>>>
>>>> I set x = "Obs" and y = "Forecast" below.
>>>>
>>>> The plot I get spreads the obs and forecast data on the x axis (where
>>>> the x axis conforms to the value of each).
>>>>
>>>> The y axis is labeled "Frequency."
>>>>
>>>> However, this is not a histogram/bar graph I am familiar with.  I am
>>>> not sure how frequency is calculated (perhaps out of the total). In any
>>>> case, I want to plot the x axis as intervals of 0 to 100 (by 10).  I want
>>>> the y-axis to show the values in the obs/forecasts that conform to these
>>>> intervals.  (Kaleidagraph can do this easily, but that's not the point
>>>> (obviously)).
>>>>
>>>> I see no such example of how to do this  -- even though this is often
>>>> how bar graphs are presented.
>>>>
>>>> Thank you for your suggestions.
>>>>
>>>> Barry
>>>>
>>>>   z = new((/2,dimsizes(x)/),integer)
>>>>   z(0,:) = x
>>>>   z(1,:) = y
>>>>
>>>> Percent, Obs, Forecast
>>>>
>>>>     0    0.0,    0.0,
>>>>
>>>>     1  227.0,  212.2,
>>>>
>>>>     4  375.0,  176.7,
>>>>
>>>>     8  201.0,  141.1,
>>>>
>>>>    12   62.0,  143.2,
>>>>
>>>>    18   26.0,  327.5,
>>>>
>>>>    24    6.0,  199.5,
>>>>
>>>>    30    1.0,   50.2,
>>>>
>>>>    36    2.0,    9.4,
>>>>
>>>>   100    0.0,    4.0,
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> --
>>>> 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>
>>>>
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>>>>
>>>>
>>>
>>
>>
>> --
>> 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
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