Adding a constraint for velocity increasing with depth about evodcinv

[keurfonluu]

Hi @ariellellouch,

That was actually planned, I just didn't have time to implement such feature. But basically, right now, it's possible to do it by:

• manually initializing the population with only increasing velocity models (yet still random)
• adding a penalty term for models that do not satisfy that constraint (via argument extra_terms in configure)

But it will definitely be better to have a boolean option to automate that.

[ariellellouch]

Thanks!
I am a bit scared to play with the extra_terms without an example, but will give it a go! :)

Edit:
Quick and dirty solution which assures Vs is going up with depth (I'm sure this can be made prettier and not depend on the structure of x, but I am not a good enough coder). Adding extra_terms=inc_misfit works for me.

def inc_misfit(x):
nel = int((np.size(x)-2)/3)
return 999999.9 * np.any(np.diff(x[nel:2*nel+1])<0)

[keurfonluu]

As long as it works!

I added an option increasing_velocity in configure that initializes the population with increasing velocity models, and adds a penalty term to reject generated models given the constraint:

model.configure(
    optimizer="cpso",  # Evolutionary algorithm
    misfit="rmse",  # Misfit function type
    optimizer_args={
        "popsize": 10,  # Population size
        "maxiter": 100,  # Number of iterations
        "workers": -1,  # Number of cores
        "seed": 0,
    },
    increasing_velocity=True,
)

You can update to evodcinv v2.1.1: pip install evodcinv -U.

[ariellellouch]

Fantastic, thanks again and sorry for bugging you :)