[ncl-talk] Getting dates when a specific contour line is within a region

[Dave Allured - NOAA Affiliate]

Here is another method that is more straightforward than counting.  It is
rather obvious, sorry.  I wish I had thought of this sooner.  Just use the
min and max values of each domain grid.

    subset = vp(:, {2:25}, {100:130})
    xmin = dim_min_n (subset, (/ 1,2 /) )
    xmax = dim_max_n (subset, (/ 1,2 /) )

    has_zero = ((xmin * xmax) .le. 0)

The result is a 1-D array, true or false for each time step.  This is much
easier to resolve than the counting method.  This also handles missing
values gracefully.


On Sun, Feb 14, 2021 at 9:28 AM Dave Allured - NOAA Affiliate <
dave.allured at noaa.gov> wrote:

> My mistake, sorry.  I meant to say the function *dim_num_n*, not
> *dim_sum_n*.
>
>
> On Sun, Feb 14, 2021 at 8:30 AM Lyndz <olagueralyndonmark429 at gmail.com>
> wrote:
>
>> Hi Sir Dave,NCL-experts,
>>
>> Thank you for your suggestion. I tried this but encountered a mismatch
>> error:
>>
>> fatal:Argument type mismatch on argument (0) of (dim_sum_n) can not coerce
>>
>>
>> The printVarSummary() of *subset()* is as follows:
>>
>>
>> Variable: subset
>>
>> Type: float
>>
>> Total Size: 16120 bytes
>>
>>             4030 values
>>
>> Number of Dimensions: 3
>>
>> Dimensions and sizes: [time | 31] x [lat | 10] x [lon | 13]
>>
>> Coordinates:
>>
>>             time: [1929912..1930632]
>>
>>             lat: [2.5..25]
>>
>>             lon: [100..130]
>>
>>
>> I uploaded the files hre (chi_mar_2020.nc):
>> https://www.dropbox.com/sh/t88oab9txej73u1/AAAkDCcsTC3_eHg8uBc0vhtda?dl=0
>>
>> Any idea how to solve this?
>>
>> Sincerely,
>>
>> Lyndz
>>
>
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