bugfix and added test for acquisition scheme

dmipy/core/acquisition_scheme.py

@@ -117,7 +117,7 @@ def __init__(self, bvalues, gradient_directions, qvalues,
             if self.qvalues is not None:
                 self.shell_qvalues = self.qvalues[first_indices]
             self.shell_gradient_strengths = None
-            if self.shell_gradient_strengths is not None:
+            if self.gradient_strengths is not None:
                 self.shell_gradient_strengths = (
                     self.gradient_strengths[first_indices])
             self.shell_delta = None
@@ -895,18 +895,22 @@ def gtab_dmipy2dipy(dmipy_gradient_table):
     delta = dmipy_gradient_table.delta
     Delta = dmipy_gradient_table.Delta
 
-    if len(np.unique(delta)) == 1:
-        delta = delta[0]
-    elif len(np.unique(delta)) > 1:
+    if len(np.unique(delta)) > 1:
         msg = "Cannot create Dipy GradientTable for Acquisition schemes with "
         msg += "multiple delta (pulse duration) values, due to current "
         msg += "limitations of Dipy GradientTables."
-    if len(np.unique(Delta)) == 1:
-        Delta = Delta[0]
-    elif len(np.unique(Delta)) > 1:
+        raise ValueError(msg)
+    elif len(np.unique(delta)) == 1:
+        delta = delta[0]
+
+    if len(np.unique(Delta)) > 1:
         msg = "Cannot create Dipy GradientTable for Acquisition schemes with "
         msg += "multiple Delta (pulse sepration) values, due to current "
         msg += "limitations of Dipy GradientTables."
+        raise ValueError(msg)
+    elif len(np.unique(Delta)) == 1:
+        Delta = Delta[0]
+
     dipy_gradient_table = gradient_table(
         bvals=bvals, bvecs=bvecs, small_delta=delta, big_delta=Delta)
     return dipy_gradient_table

dmipy/core/tests/test_acquisition_scheme.py

@@ -1,4 +1,6 @@
 import numpy as np
+from dmipy.data.saved_acquisition_schemes import (
+    duval_cat_spinal_cord_2d_acquisition_scheme)
 from dmipy.core.acquisition_scheme import (
     acquisition_scheme_from_bvalues,
     acquisition_scheme_from_qvalues,
@@ -143,7 +145,7 @@ def test_estimate_shell_indices():
     assert_array_equal(shell_indices, bvalues)
 
 
-def test_shell_indices_with_vayring_diffusion_times(Nsamples=10):
+def test_shell_indices_with_varying_diffusion_times(Nsamples=10):
     # tests whether measurements with the same bvalue but different diffusion
     # time are correctly classified in different shells
     bvalues = np.tile(1e9, Nsamples)
@@ -156,7 +158,7 @@ def test_shell_indices_with_vayring_diffusion_times(Nsamples=10):
     assert_equal(len(np.unique(scheme.shell_indices)), 2)
 
 
-def test_dipy2mipy_acquisition_converter(Nsamples=10):
+def test_dipy2dmipy_acquisition_converter(Nsamples=10):
     bvals = np.tile(1e3, Nsamples)
     bvecs = np.tile(np.r_[1., 0., 0.], (Nsamples, 1))
     big_delta = 0.03
@@ -170,7 +172,7 @@ def test_dipy2mipy_acquisition_converter(Nsamples=10):
     assert_equal(np.unique(gtab_mipy.delta), gtab_dipy.small_delta)
 
 
-def test_mipy2dipy_acquisition_converter(Nsamples=10):
+def test_dmipy2dipy_acquisition_converter(Nsamples=10):
     bvals = np.tile(1e9, Nsamples)
     bvecs = np.tile(np.r_[1., 0., 0.], (Nsamples, 1))
     big_delta = 0.03
@@ -194,3 +196,8 @@ def test_acquisition_scheme_summary(Nsamples=10):
         bvalues=bvals, gradient_directions=bvecs,
         delta=small_delta, Delta=big_delta)
     gtab_mipy.print_acquisition_info
+
+
+def test_raise_dmipy2dmipy_multiple_delta_Delta():
+    scheme = duval_cat_spinal_cord_2d_acquisition_scheme()
+    assert_raises(ValueError, gtab_dmipy2dipy, scheme)