diff --git a/libraries/base/common/python/try_round_weight.py b/libraries/base/common/python/try_round_weight.py index 35ef0b31f2e49ada3036626b3d8d9bfff3880c39..ad02822219dec00c927ba1a896b4524ffc51e1f3 100644 --- a/libraries/base/common/python/try_round_weight.py +++ b/libraries/base/common/python/try_round_weight.py @@ -34,10 +34,15 @@ # . increasing -N improves the results, for LOFAR subbands N = 195312 # . it may be preferred to apply the subband weights to the unquantized # WPFB output. -# Usage: +# Note: +# . For values exactly halfway between rounded decimal values, NumPy rounds to +# the nearest even value. Thus 1.5 and 2.5 round to 2.0, -0.5 and 0.5 round +# to 0.0, etc. +# Usage: # > python3 try_round_weight.py -N 195312 import argparse +import textwrap import numpy as np import matplotlib @@ -47,9 +52,33 @@ import matplotlib.pyplot as plt import common as cm # Parse arguments to derive user parameters -_parser = argparse.ArgumentParser('try_round_weight') +_parser = argparse.ArgumentParser( + description="".join(textwrap.dedent("""\ + Model effect of applying a weight after or before rounding: + + . weights in range(w_lo, w_hi, w_step) + . sigma of noise in range(s_lo, s_hi, s_step) + . use N = 195312 to model number of subband periods in 1 s of LOFAR SST + . use different seed S to check whether result in plots depends on seed + . use r = 0 for default integer rounding, use r > 0 to have extra + LSbits resolution before rounding + . use f = 0 for full double resolution before rounding, use f > 0 and + r = 0 to have noise with a fraction of f LSbits before rounding + + # Get an overview + > python try_round_weight.py --w_lo 0.2 --w_hi 3.0 --w_step 0.01 --s_lo 0.5 --s_hi 10 --s_step 0.2 -N 195312 -S 1 + + # Zoom in at w = 0.75 + > python try_round_weight.py --w_lo 0.7 --w_hi 0.8 --w_step 0.0001 --s_lo 1 --s_hi 10 --s_step 1 -N 195312 -S 0 + + # Use -r = 6 to see effect of having more resolution before rounding + > python try_round_weight.py --w_lo 0.7 --w_hi 0.8 --w_step 0.0001 --s_lo 1 --s_hi 10 --s_step 1 -N 195312 -S 0 -r 6 + \n""")), + formatter_class=argparse.RawTextHelpFormatter) _parser.add_argument('-S', default=0, type=int, help='Random number seed') _parser.add_argument('-N', default=1000, type=int, help='Number of input samples') +_parser.add_argument('-f', default=0, type=int, help='Number of LSbits in fraction, use default 0 for double accuracy') +_parser.add_argument('-r', default=0, type=int, help='Number of LSbits extra resolution before rounding') _parser.add_argument('--s_lo', default=0.1, type=float, help='Lowest sigma') _parser.add_argument('--s_hi', default=25.0, type=float, help='Highest sigma') _parser.add_argument('--s_step', default=0.1, type=float, help='Step sigma') @@ -63,7 +92,6 @@ np.random.seed(args.S) # Prepare noise signal N_samples = args.N noise = np.random.randn(N_samples) -noise = np.random.randn(N_samples) noise /= np.std(noise) # Noise levels range, 1 unit = 1 LSbit @@ -80,13 +108,32 @@ weight_step = args.w_step weights = np.arange(weight_lo, weight_hi, weight_step) N_weights = len(weights) +# Fraction +fraction = args.f +fraction_factor = 2**fraction + +# Resolution +resolution = args.r +resolution_factor = 2**resolution + # Determine weighted rounded noise sigma / weighted noise sigma for range of weights and input noise sigmas sigmas_ratio = np.nan * np.zeros((N_weights, N_sigmas)) # w rows, s cols sigmas_qq = np.zeros((N_weights, N_sigmas)) sigmas_sq = np.zeros((N_weights, N_sigmas)) for s, sigma in enumerate(sigmas): noise_s = noise * sigma - noise_q = np.round(noise_s) + if resolution == 0: + if fraction == 0: + # Default use full double resolution of fraction of noise_s + noise_q = np.round(noise_s) + else: + # First use round() to get noise_f with a fraction of fraction number of LSbits + noise_f = np.round(noise_s * fraction_factor) / fraction_factor + # Then use round to round the fraction of fraction number of LSbits in noise_f + noise_q = np.round(noise_f) + else: + noise_q = np.round(noise_s * resolution_factor) / resolution_factor + for w, weight in enumerate(weights): noise_q_weighted_q = np.round(noise_q * weight) # apply weight to rounded noise noise_s_weighted_q = np.round(noise_s * weight) # apply weight to original noise @@ -110,7 +157,7 @@ for s, sigma in enumerate(sigmas): plt.plot(weights, sigmas_qq_T[s], label='s = %4.2f' % sigma) plt.title("Sigma of weighted quantized noise") plt.xlabel("Weight") -plt.ylabel("Sigma") +plt.ylabel("Sigma_qq") plt.legend(loc='upper right') plt.grid() @@ -130,7 +177,7 @@ for w, weight in enumerate(weights): plt.plot(sigmas, sigmas_ratio[w], label='w = %4.2f' % weight) plt.title("Relative sigma difference of weighting after / before quantisation") plt.xlabel("Sigma") -plt.ylabel("Relative sigma difference") +plt.ylabel("Relative sigma difference (s_qq / s_sq)") plt.legend(loc='upper right') plt.grid()