09: Add argparse interface

Exercise sheet 9/exercise_sheet_09.ipynb

@@ -231,6 +231,33 @@
     "plt.show()"
    ]
   },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "e506d9a5",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "import h5py\n",
+    "import numpy as np\n",
+    "from matplotlib import pyplot as plt\n",
+    "\n",
+    "# Load data\n",
+    "output_filename = \"preliminary_simulation.h5\"\n",
+    "with h5py.File(output_filename,'r') as f:\n",
+    "    handler = f[\"mean-magn\"]\n",
+    "    mean_magn = np.array(handler)\n",
+    "    kappas = handler.attrs[\"kappas\"]\n",
+    "\n",
+    "# Plotterdeplotterdeplot\n",
+    "plt.figure()\n",
+    "plt.errorbar(kappas,[m[0] for m in mean_magn],yerr=[m[1] for m in mean_magn],fmt='-o')\n",
+    "plt.xlabel(r\"$\\kappa$\")\n",
+    "plt.ylabel(r\"$|m|$\")\n",
+    "plt.title(r\"Absolute field average on $3^4$ lattice, $\\lambda = 1.5$\")\n",
+    "plt.show()"
+   ]
+  },
   {
    "cell_type": "markdown",
    "id": "d4640925",

Exercise sheet 9/latticescalar.py

@@ -1,3 +1,5 @@
+__doc__ = "Simulates a lattice scalar field using the Metropolis-Hastings algorithm."
+
 import numpy as np
 import argparse
 import time
@@ -49,33 +51,64 @@ def batch_estimate(data,observable,k):
 	return np.mean(values), np.std(values)/np.sqrt(k-1)
 
 def main():
-	lamb = 1.5
-	kappas = np.linspace(0.08,0.18,11)
-	width = 3
+	# use the argparse package to parse command line arguments
+	parser = argparse.ArgumentParser(description=__doc__)
+	# TODO: Describe what lambda, delta, and kappa really mean.
+	parser.add_argument('-l', type=float, default=1.5, help='lambda')
+	parser.add_argument('-k', type=float, default=0.08, help='kappa')
+	parser.add_argument('-w', type=int, default=3, help='Width w of the square lattice.')
+	# delta = 1.5 chosen to have ~ 50% acceptance
+	parser.add_argument('-d', type=int, default=1.5, help='delta')
+	parser.add_argument('-n', type=int, help='Number N of measurements (indefinite by default)')
+	parser.add_argument('-e', type=int, default=100, help='Number E of equilibration sweeps')
+	parser.add_argument('-m', type=int, default=2, help='Number M of sweeps per measurement')
+	parser.add_argument('-o', type=int, default=30, help='Time in seconds between file outputs')
+	parser.add_argument('-f', help='Output filename')
+	args = parser.parse_args()
+	
+	# perform sanity checks on the arguments
+	if args.w is None or args.w < 1:
+	    parser.error("Please specify a positive lattice size!")
+	if args.k is None or args.k <= 0.0:
+	    parser.error("Please specify a positive kappa!")
+	if args.e < 10:
+	    parser.error("Need at least 10 equilibration sweeps to determine the average cluster size")
+	if args.d < 1:
+	    parser.error("Delta should be >= 1.")
+	
+	# fix parameters
+	lamb = args.l
+	kappa = args.k
+	width = args.w
 	num_sites = width**4
-	delta = 1.5  # chosen to have ~ 50% acceptance
-	equil_sweeps = 10
-	measure_sweeps = 2
-	measurements = 20
-	
+	delta = args.d
+	equil_sweeps = args.e
+	measure_sweeps = args.m
+	measurements = args.n
+	if args.f is None:
+	    # construct a filename from the parameters plus a timestamp (to avoid overwriting)
+	    output_filename = "data_l{}_k{}_w{}_d{}_{}.hdf5".format(lamb,kappa,width,delta,time.strftime("%Y%m%d%H%M%S"))
+	else:
+	    output_filename = args.f
+
+	# Measure
+	# TODO: Does mean_magn need to be a list?
 	mean_magn = []
-	for kappa in kappas:
-		phi_state = np.zeros((width,width,width,width))
-		run_scalar_MH(phi_state,lamb,kappa,delta,equil_sweeps * num_sites)
-		magnetizations = np.empty(measurements)
-		for i in range(measurements):
-			run_scalar_MH(phi_state,lamb,kappa,delta,measure_sweeps * num_sites)
-			magnetizations[i] = np.mean(phi_state)
-		mean, err = batch_estimate(np.abs(magnetizations),lambda x:np.mean(x),10)
-		mean_magn.append([mean,err])
+	phi_state = np.zeros((width,width,width,width))
+	run_scalar_MH(phi_state,lamb,kappa,delta,equil_sweeps * num_sites)
+	magnetizations = np.empty(measurements)
+	for i in range(measurements):
+		run_scalar_MH(phi_state,lamb,kappa,delta,measure_sweeps * num_sites)
+		magnetizations[i] = np.mean(phi_state)
+	mean, err = batch_estimate(np.abs(magnetizations),lambda x:np.mean(x),10)
+	mean_magn.append([mean,err])
 	
-	output_filename = 'preliminary_simulation.h5'
 	with h5py.File(output_filename,'a') as f:
 		if not "mean-magn" in f:
 			dataset = f.create_dataset("mean-magn", chunks=True, data=mean_magn)
 			# store some information as metadata for the data set
 			dataset.attrs["lamb"] = lamb
-			dataset.attrs["kappas"] = kappas
+			dataset.attrs["kappa"] = kappa
 			dataset.attrs["width"] = width
 			dataset.attrs["num_sites"] = num_sites
 			dataset.attrs["delta"] = delta