Fix #79: add scan_from_param and test case

concert/processes.py

@@ -38,6 +38,22 @@ def scan(param, feedback, minimum=None, maximum=None, intervals=64,
     return (xss, yss)
 
 
+def scan_from_param(scan_param, feedback_param,
+                    minimum=None, maximum=None, intervals=64,
+                    convert=lambda x: x):
+    """Convenience function to scan one parameter and measure another.
+
+    Scan the *scan_param* object and measure *feedback_param* at each of the
+    *intervals* steps between *minimum* and *maximum*.
+
+    Returns a tuple *(x, y)* with scanned parameter and measured values.
+    """
+    def feedback():
+        return feedback_param.get().result()
+
+    return scan(scan_param, feedback, minimum, maximum, intervals, convert)
+
+
 def ascan(param_list, n_intervals, handler, initial_values=None):
     """
     For each of the *n_intervals* and for each of the *(parameter, start,

concert/tests/integration/processes/test_scan.py

@@ -2,7 +2,7 @@
 from concert.tests import assert_almost_equal
 from concert.devices.motors.dummy import Motor as DummyMotor
 from concert.devices.cameras.dummy import Camera
-from concert.processes import scan, ascan, dscan
+from concert.processes import scan, ascan, dscan, scan_from_param
 from concert.tests import slow
 from concert.tests.base import ConcertTest
 
@@ -49,3 +49,8 @@ def feedback():
         x, y = scan(self.motor['position'], feedback,
                     1 * q.mm, 10 * q.mm, 10).result()
         compare_sequences(x, y, self.assertEqual)
+
+    def test_scan_from_param(self):
+        p = self.motor['position']
+        x, y = scan_from_param(p, p, 1 * q.mm, 10 * q.mm, 10).result()
+        compare_sequences(x, y, self.assertEqual)