[ncl-talk] Detecting local_minima of a time series with a specified length (local_min_1d)
Lyndz
olagueralyndonmark429 at gmail.com
Mon Feb 5 20:09:08 MST 2018
Dear NCL experts,
I am trying to locate the local minima in a time series (1D) but with
additional condition that it has at least 2 decreasing adjacent
points(before or after the local minima).
Here's an example
* x = (/35.91,22.43,15.84,6.62,4.71,9.67,12.25,2.01,30.25,85.64/)*
To detect the local minima I used the following commands:
*qmin=local_min_1d(x,False,-0.25,0)*
* print(qmin)*
This gives the following:
* Variable: qmin *
* Type: float *
* Total Size: 8 bytes*
* 2 values*
* Number of Dimensions: 1*
* Dimensions and sizes: [2]*
* Coordinates: *
* (0) 4.71*
* (1) 2.01*
The answer to my problem above should be the (0) 4.71 since the 2.01 is an
abrupt decrease.
Here's another example:
* y = (/14.52,20.50,22.43,3.18,9.39,10.95,65.38,40.45,5.89,16.75/)*
*qmin=local_min_1d(y,False,-0.25,0)*
* print(qmin)*
* Variable: qmin*
* Type: float*
* Total Size: 8 bytes*
* 2 values*
* Number of Dimensions: 1*
* Dimensions and sizes: [2]*
* Coordinates: *
* (0) 3.18*
* (1) 5.89*
The answer here should be the (0) 3.18. The second one is also an abrupt
decrease.
Is there an efficient way to implement this in NCL? I will be applying this
for many csv files.
I'll appreciate any suggestion.
Sincerely,
Lyndz
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