ENH: Enable percentile value limits

Author: effigies

nibabel/viewers.py

@@ -64,7 +64,8 @@ def __init__(self, data, affine=None, axes=None, title=None, vlim=None,
             title.
         vlim : array-like or None, optional
             Value limits to display image and time series. Can be None
-            (default) to derive limits from data.
+            (default) to derive limits from data. Bounds can be of the
+            form ``'x%'`` to use the ``x`` percentile of the data.
         slicer : object or None
             Something that can be used to slice an array as in
             ``arr[sliceobj]``. Can be None (default) to display all data.
@@ -87,6 +88,13 @@ def __init__(self, data, affine=None, axes=None, title=None, vlim=None,
         affine = np.array(affine, float) if affine is not None else np.eye(4)
         if affine.shape != (4, 4):
             raise ValueError('affine must be a 4x4 matrix')
+
+        if vlim is not None:
+            vlim = [float(lim[:-1]) / 100
+                    if isinstance(lim, str) and lim.endswith('%')
+                    else lim
+                    for lim in vlim]
+
         # determine our orientation
         self._affine = affine
         codes = axcodes2ornt(aff2axcodes(self._affine))