FIX: Switch to mode of central 90% of value range

Author: effigies

sdcflows/interfaces/fmap.py

@@ -661,18 +661,19 @@ def _delta_te(in_values, te1=None, te2=None):
 
 def au2rads(in_file, newpath=None):
     """Convert the input phase difference map in arbitrary units (a.u.) to rads."""
+    from scipy import stats
     im = nb.load(in_file)
     data = im.get_fdata(dtype='float32')
     hdr = im.header.copy()
 
-    vals, counts = np.unique(data, return_counts=True)
-    modes = vals[np.argsort(counts)[::-1]]
+    dmin, dmax = data.min(), data.max()
 
-    # Second mode (idx 1) if first node (idx 0) is minimum, else first
-    idx = int(modes[0] == data.min())
+    # Find the mode ignoring outliers on the far max/min, to allow for junk outside the FoV
+    fudge = 0.05 * (dmax - dmin)
+    mode = stats.mode(data[(data > dmin + fudge) & (data < dmax - fudge)])[0][0]
 
     # Center data around 0.0
-    data -= modes[idx]
+    data -= mode
 
     # Provide a less opaque error if we still can't figure it out
     neg = data < 0