add method minBy

README.md

@@ -512,7 +512,7 @@ we will compare with str(a) and str(b).
 R.Min('A', None) # 'A', 'A' < 'None'
 ```
 
-- [ ] minBy
+- [x] minBy
 - [ ] modify
 - [ ] modifyPath
 - [x] 0.1.4 modulo

ramda/__init__.py

@@ -79,6 +79,7 @@
 from .mathMod import mathMod
 from .Max import Max
 from .Min import Min
+from .minBy import minBy
 from .modulo import modulo
 from .multiply import multiply
 from .nAry import nAry

ramda/minBy.py

@@ -0,0 +1,10 @@
+from .Min import Min
+from .private._curry3 import _curry3
+
+
+def inner_minBy(f, a, b):
+  resultB = f(b)
+  return b if Min(f(a), resultB) == resultB else a
+
+
+minBy = _curry3(inner_minBy)

test/test_minBy.py

@@ -0,0 +1,18 @@
+
+import unittest
+
+import ramda as R
+
+"""
+https://github.com/ramda/ramda/blob/master/test/minBy.js
+"""
+
+
+class TestMinBy(unittest.TestCase):
+  def test_returns_the_smaller_value_as_determined_by_the_function(self):
+    self.assertEqual(2, R.minBy(lambda x: x * x, -3, 2))
+    self.assertEqual({'x': 3, 'y': 1}, R.minBy(R.prop('x'), {'x': 3, 'y': 1}, {'x': 5, 'y': 10}))
+
+
+if __name__ == '__main__':
+  unittest.main()