Currently, opimize_kl opens a new figure, when plotting the minisanity history, in every iteration of the optimisation (See this line in the code: https://gitlab.mpcdf.mpg.de/ift/nifty/-/blob/NIFTy_8/src/minimization/optimize_kl.py#L613). After the minisanity plot the figure is cleared but not closed. Thus after an optimize_kl run with n iterations, there are n open matplotlib figures. If one calls plt.show() after optimize_kl n empty figures will open. Here is a small demo:
import nifty8 as ift
import matplotlib.pyplot as plt
import numpy as np
from mpi4py import MPI
comm = MPI.COMM_WORLD
master = comm.Get_rank() == 0
############ some nifty with optimize_kl ##############
sp = ift.RGSpace(1)
op = ift.makeOp(ift.full(sp, 1)).ducktape('blub')
d = ift.full(sp, 1.)
n = ift.ScalingOperator(sp, 0.1, np.float64)
lh = ift.GaussianEnergy(d, inverse_covariance=n.inverse) @ op
n_iterations = 3
n_samples = 2
ic_sampling = ift.AbsDeltaEnergyController(name="Sampling (linear)",
deltaE=0.05, iteration_limit=100)
ic_newton = ift.AbsDeltaEnergyController(name='Newton', deltaE=0.5,
convergence_level=2, iteration_limit=35)
ic_sampling_nl = ift.AbsDeltaEnergyController(name='Sampling (nonlin)',
deltaE=0.5, iteration_limit=15,
convergence_level=2)
minimizer = ift.NewtonCG(ic_newton)
minimizer_sampling = ift.NewtonCG(ic_sampling_nl)
samples = ift.optimize_kl(lh, n_iterations, 2,
minimizer, ic_sampling, minimizer_sampling,
output_directory="folder",
comm=comm, plot_energy_history=True,
plot_minisanity_history=True)
#######################################################
x = np.linspace(1,10,100)
plt.plot(x,x**2)
if master:
plt.show()
Is there a reason to create a new figure every time? I guess this is a bug. I have removed the plt.figure(). Note: also in the energy history we don't have a plt.figure().