graph_accelerometer: Add tool to graph accelerometer results

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

scripts/graph_accelerometer.py

@@ -0,0 +1,78 @@
+#!/usr/bin/env python2
+# Generate adxl345 accelerometer graphs
+#
+# Copyright (C) 2020  Kevin O'Connor <kevin@koconnor.net>
+#
+# This file may be distributed under the terms of the GNU GPLv3 license.
+import optparse
+import matplotlib
+
+def parse_log(logname):
+    f = open(logname, 'r')
+    out = []
+    for line in f:
+        if line.startswith('#'):
+            continue
+        parts = line.split(',')
+        if len(parts) != 4:
+            continue
+        try:
+            fparts = [float(p) for p in parts]
+        except ValueError:
+            continue
+        out.append(fparts)
+    return out
+
+def plot_accel(data, logname):
+    half_smooth_samples = 15
+    first_time = data[0][0]
+    times = [d[0] - first_time for d in data]
+    fig, axes = matplotlib.pyplot.subplots(nrows=3, sharex=True)
+    axes[0].set_title("Accelerometer data (%s)" % (logname,))
+    axis_names = ['x', 'y', 'z']
+    for i in range(len(axis_names)):
+        adata = [d[i+1] for d in data]
+        avg = sum(adata) / len(adata)
+        adata = [ad - avg for ad in adata]
+        ax = axes[i]
+        ax.plot(times, adata, alpha=0.8)
+        ax.grid(True)
+        ax.set_ylabel('%s accel (%+.3f)\n(mm/s^2)' % (axis_names[i], -avg))
+    axes[-1].set_xlabel('Time (%+.3f)\n(s)' % (-first_time,))
+    fig.tight_layout()
+    return fig
+
+def setup_matplotlib(output_to_file):
+    global matplotlib
+    if output_to_file:
+        matplotlib.rcParams.update({'figure.autolayout': True})
+        matplotlib.use('Agg')
+    import matplotlib.pyplot, matplotlib.dates, matplotlib.font_manager
+    import matplotlib.ticker
+
+def main():
+    # Parse command-line arguments
+    usage = "%prog [options] <log>"
+    opts = optparse.OptionParser(usage)
+    opts.add_option("-o", "--output", type="string", dest="output",
+                    default=None, help="filename of output graph")
+    options, args = opts.parse_args()
+    if len(args) != 1:
+        opts.error("Incorrect number of arguments")
+
+    # Parse data
+    data = parse_log(args[0])
+
+    # Draw graph
+    setup_matplotlib(options.output is not None)
+    fig = plot_accel(data, args[0])
+
+    # Show graph
+    if options.output is None:
+        matplotlib.pyplot.show()
+    else:
+        fig.set_size_inches(8, 6)
+        fig.savefig(options.output)
+
+if __name__ == '__main__':
+    main()