Index at bug

nitime/tests/test_timeseries.py

@@ -588,4 +588,21 @@ def test_Events():
         yield npt.assert_equal(ev2.index.i1,i1)
 
 
+@decotest.parametric
+def test_index_at_20101206():
+    """Test for incorrect handling of negative t0 for time.index_at
 
+    https://github.com/nipy/nitime/issues#issue/35 
+
+    bug reported by Jonathan Taylor on 2010-12-06
+    """
+    A=np.random.standard_normal(40)
+    #negative t0
+    TS_A=ts.TimeSeries(A,t0=-20,sampling_interval=2)
+    yield npt.assert_equal(TS_A.time.index_at(TS_A.time),np.arange(40))
+    #positive t0
+    TS_A=ts.TimeSeries(A,t0=15,sampling_interval=2)
+    yield npt.assert_equal(TS_A.time.index_at(TS_A.time),np.arange(40))
+    #no t0
+    TS_A=ts.TimeSeries(A,sampling_interval=2)
+    yield npt.assert_equal(TS_A.time.index_at(TS_A.time),np.arange(40))

nitime/timeseries.py

@@ -551,9 +551,7 @@ def index_at(self,t,boolean=False):
         # check that index is within range
         if ta.min() < self.t0 or ta.max() >= self.t0 + self.duration:
             raise ValueError, 'index out of range'
-
-        idx = ta.view(np.ndarray)//int(self.sampling_interval) 
-        idx -= self.t0/self._conversion_factor
+        idx = (ta.view(np.ndarray) - self.t0)//self.sampling_interval
         if boolean:
             bool_idx = np.zeros(len(self),dtype=bool)
             bool_idx[idx] = True