Optimize the way data in unpacked (#9)

Optimize the way data in unpacked

Author: mrmcwethy

adafruit_lis3dh/lis3dh.py

@@ -98,10 +98,6 @@ def acceleration(self):
         """Read the x, y, z acceleration values.  These values are returned in
         a 3-tuple and are in m / s ^ 2.
         """
-        data = self._read_register(REG_OUT_X_L | 0x80, 6)
-        x = struct.unpack('<h', data[0:2])[0]
-        y = struct.unpack('<h', data[2:4])[0]
-        z = struct.unpack('<h', data[4:6])[0]
         divider = 1
         accel_range = self.range
         if accel_range == RANGE_16_G:
@@ -112,6 +108,9 @@ def acceleration(self):
             divider = 8190
         elif accel_range == RANGE_2_G:
             divider = 16380
+
+        x, y, z = struct.unpack('<hhh', self._read_register(REG_OUT_X_L | 0x80, 6))
+        
         return (x / divider * 9.806, y / divider * 9.806, z / divider * 9.806)
 
     def read_adc_raw(self, adc):
@@ -120,8 +119,8 @@ def read_adc_raw(self, adc):
         """
         if adc < 1 or adc > 3:
             raise ValueError('ADC must be a value 1 to 3!')
-        data = self._read_register((REG_OUTADC1_L+((adc-1)*2)) | 0x80, 2)
-        return struct.unpack('<h', data[0:2])[0]
+
+        return struct.unpack('<h', self._read_register((REG_OUTADC1_L+((adc-1)*2)) | 0x80, 2))[0]
 
     def read_adc_mV(self, adc):
         """Read the specified analog to digital converter value in millivolts.