make python bandrank() work like bandjoin()

we had a custom wrapper for bandjoin(), but bandrank(), a function with
an almost identical interface, did not ... this was confusing

bandrank() now has a custom wrapper too ... this breaks API
unfortunately, but hopefully very few people were using this thing and
it's better to make this change as soon as possible

ChangeLog

@@ -17,6 +17,7 @@
 - vipsthumbnail knows about webp shrink-on-load
 - more vips_resize() tuning, a bit quicker now
 - better behaviour for vips_cast() shift of non-int types (thanks apacheark)
+- python .bandrank() now works like .bandjoin()
 
 27/1/16 started 8.2.3
 - fix a crash with SPARC byte-order labq vips images

TODO

@@ -1,34 +1,8 @@
-better handling of cast+shift for non-int formats
-
-before, im.cast(uchar, shift = true) where im was float and tagged as 
-rgb16 would not shift the image, since it's unclear how much to shift a float 
-type by
-
-now we do two casts: first, we guess the numeric range from the
-interpretation, so rgb16 would be ushort, so we cast float->ushort;
-second, we cast to the target type and do the shift on the way
-
-
-- python bandrank should work like bandjoin
 
 - try SEQ_UNBUFFERED on jpg source, get out of order error?
 
 - could load pdf thumbnails?
 
-- new vips_reduce:
-
-	affine
-	$ time vipsthumbnail wtc.tif -o x.tif -s 7000
-	real	0m2.325s
-	user	0m8.316s
-	sys	0m0.256s
-
-	reduce
-	$ time vipsthumbnail wtc.tif -o x.tif -s 7000
-	real	0m1.677s
-	user	0m5.996s
-	sys	0m0.300s
-
 - get some brightly coloured spots with nohalo / vsqbs on wobble.ws ... very
   odd, the interpolation shouldn't change between bands
 
@@ -36,12 +10,6 @@ second, we cast to the target type and do the shift on the way
 
 - still not happy about float->int mask conversion in im_vips2mask.c
 
-- need to follow up on
-
-	https://github.com/jcupitt/libvips/issues/347
-
-  trying new shrinker, also try resize change, should be fixed
-
 - colour needs to split _build() into preprocess / process / postprocess
   phases
 

python/Vips.py

@@ -930,6 +930,13 @@ class Image(Vips.Image):
         else:
             return _call_base("bandjoin", [[self] + other], {})
 
+    def bandrank(self, other, **kwargs):
+        """Band-wise rank filter a set of images."""
+        if not isinstance(other, list):
+            other = [other]
+
+        return _call_base("bandrank", [[self] + other], kwargs)
+
     def maxpos(self):
         """Return the coordinates of the image maximum."""
         v, opts = self.max(x = True, y = True)
@@ -1055,14 +1062,13 @@ class Image(Vips.Image):
 
 # use find_class_methods.py to generate this list
 
-# don't include "bandjoin", this needs to be wrapped by hand, see
-# above
+# don't include "bandjoin" or "bandrank", they need to be wrapped by hand, 
+# see above
 
 class_methods = [
                     "system",
                     "sum",
                     "arrayjoin",
-                    "bandrank",
                     "black",
                     "gaussnoise",
                     "text",

python/find_class_methods.py

@@ -49,7 +49,7 @@ print 'found class methods:'
 names = find_class_methods(vips_type_operation)
 
 # filter out things we know we should not wrap
-names -= set(["bandjoin"])
+names -= set(["bandjoin", "bandrank"])
 
 names = list(names)
 names.sort()

test/test_conversion.py

@@ -208,12 +208,17 @@ class TestConversion(unittest.TestCase):
 
         def bandrank(x, y):
             if isinstance(x, Vips.Image) and isinstance(y, Vips.Image):
-                return Vips.Image.bandrank([x, y])
+                return x.bandrank([y])
             else:
                 return median(x, y)
 
         self.run_binary(self.all_images, bandrank, fmt = noncomplex_formats)
 
+        # we can mix images and constants, and set the index arg
+        a = self.mono.bandrank([2], index = 0)
+        b = (self.mono < 2).ifthenelse(self.mono, 2)
+        self.assertEqual((a - b).abs().min(), 0)
+
     def test_cache(self):
         def cache(x):
             if isinstance(x, Vips.Image):