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battery_capacity.py

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+#!/usr/bin/env python
+
+import sys
+import csv
+import matplotlib.pyplot
+from pprint import pprint
+
+# Constants
+DATADIR = "data/"
+
+def parse_index(btype):
+    index = []
+    bdir = DATADIR + btype + "/"
+
+    with open(bdir + "index.csv", "rb") as f:
+        reader = csv.reader(f)
+        try:
+            for i, row in enumerate(reader):
+                if i > 0:
+                    expcap = 0
+                    if row[4] != "":
+                        expcap = int(row[4])
+
+                    index.append({
+                        "show": bool(int(row[0])),
+                        "brand": row[1],
+                        "model": row[2],
+                        "voltage": float(row[3]),
+                        "exp_capacity": expcap,
+                        "current": int(row[5]),
+                        "type": row[6],
+                        "cutoff": float(row[7]),
+                        "file": row[8],
+                        "comment": row[9]
+                    })
+        except csv.Error as err:
+            sys.exit("File %s, line %d: %s" % (filename, reader.line_num, err))
+
+    return index
+
+def parse_battery(filename, current, cutoff = 0.8):
+    mah = []
+    volts = []
+
+    with open(filename, "rb") as f:
+        reader = csv.reader(f)
+        try:
+            for i, row in enumerate(reader):
+                voltage = float(row[2])
+                mah.append(current * (float(i) / 3600))
+                volts.append(voltage)
+
+                if (voltage < cutoff):
+                    break
+        except csv.Error as err:
+            sys.exit("File %s, line %d: %s" % (filename, reader.line_num, err))
+
+    return { "mah": mah, "volts": volts }
+
+def get_batteries(btype):
+    index = parse_index(btype)
+    bdir = DATADIR + btype + "/"
+    batteries = []
+
+    for battery in index:
+        if battery["show"]:
+            batteries.append({ "name": battery["brand"] + " " + battery["model"],
+                "data": parse_battery(bdir + battery["file"], battery["current"], battery["cutoff"]) })
+
+    return batteries
+
+if __name__ == "__main__":
+    batteries = get_batteries("9V")
+
+    # Prepare the plot.
+    matplotlib.pyplot.style.use("ggplot")
+
+    for batt in batteries:
+        matplotlib.pyplot.plot(batt["data"]["mah"], batt["data"]["volts"], label = batt["name"])
+
+    # Setup the plot.
+    matplotlib.pyplot.title("Battery Discharge")
+    matplotlib.pyplot.legend(loc = "upper right")
+    matplotlib.pyplot.xlabel("Capacity (mAh)")
+    matplotlib.pyplot.ylabel("Voltage (V)")
+    matplotlib.pyplot.grid(True)
+    matplotlib.pyplot.show()
+