fixes #97

Author: jph00

fastcore/_nbdev.py

@@ -41,6 +41,7 @@
          "delegate_attr": "01_foundation.ipynb",
          "bind": "01_foundation.ipynb",
          "listable_types": "01_foundation.ipynb",
+         "first": "01_foundation.ipynb",
          "CollBase": "01_foundation.ipynb",
          "L": "01_foundation.ipynb",
          "L.__signature__": "01_foundation.ipynb",
@@ -72,7 +73,6 @@
          "is_listy": "02_utils.ipynb",
          "range_of": "02_utils.ipynb",
          "groupby": "02_utils.ipynb",
-         "first": "02_utils.ipynb",
          "last_index": "02_utils.ipynb",
          "shufflish": "02_utils.ipynb",
          "IterLen": "02_utils.ipynb",

fastcore/foundation.py

@@ -2,7 +2,7 @@
 
 __all__ = ['defaults', 'copy_func', 'patch_to', 'patch', 'patch_property', 'add_docs', 'docs', 'custom_dir', 'arg0',
            'arg1', 'arg2', 'arg3', 'arg4', 'coll_repr', 'is_bool', 'mask2idxs', 'cycle', 'zip_cycle', 'is_indexer',
-           'negate_func', 'GetAttr', 'delegate_attr', 'bind', 'listable_types', 'CollBase', 'L']
+           'negate_func', 'GetAttr', 'delegate_attr', 'bind', 'listable_types', 'first', 'CollBase', 'L']
 
 # Cell
 from .imports import *
@@ -181,6 +181,12 @@ def __call__(self, *args, **kwargs):
 # Cell
 listable_types = typing.Collection,Generator,map,filter,zip
 
+# Cell
+def first(x):
+    "First element of `x`, or None if missing"
+    try: return next(iter(x))
+    except StopIteration: return None
+
 # Cell
 class CollBase:
     "Base class for composing a list of `items`"
@@ -265,16 +271,20 @@ def range(cls, a, b=None, step=None):
         if is_coll(a): a = len(a)
         return cls(range(a,b,step) if step is not None else range(a,b) if b is not None else range(a))
 
-    def map(self, f, *args, **kwargs):
+    def map(self, f, *args, gen=False, **kwargs):
         g = (bind(f,*args,**kwargs) if callable(f)
              else f.format if isinstance(f,str)
              else f.__getitem__)
-        return self._new(map(g, self))
+        res = map(g, self)
+        if gen: return res
+        return self._new(res)
 
-    def filter(self, f, negate=False, **kwargs):
+    def filter(self, f=noop, negate=False, gen=False, **kwargs):
         if kwargs: f = partial(f,**kwargs)
         if negate: f = negate_func(f)
-        return self._new(filter(f, self))
+        res = filter(f, self)
+        if gen: return res
+        return self._new(res)
 
     def argwhere(self, f, negate=False, **kwargs):
         if kwargs: f = partial(f,**kwargs)
@@ -291,7 +301,13 @@ def itemgot(self, *idxs):
 
     def attrgot(self, k, default=None): return self.map(lambda o: o.get(k,default) if isinstance(o, dict) else getattr(o,k,default))
     def cycle(self): return cycle(self)
-    def map_dict(self, f=noop, *args, **kwargs): return {k:f(k, *args,**kwargs) for k in self}
+    def map_dict(self, f=noop, *args, gen=False, **kwargs): return {k:f(k, *args,**kwargs) for k in self}
+    def map_filter(self, f=noop, g=noop, *args, gen=False, **kwargs):
+        res = filter(g, self.map(f, *args, gen=gen, **kwargs))
+        if gen: return res
+        return self._new(res)
+    def map_first(self, f=noop, g=noop, *args, **kwargs): return first(self.map_filter(f, g, *args, gen=False, **kwargs))
+
     def starmap(self, f, *args, **kwargs): return self._new(itertools.starmap(partial(f,*args,**kwargs), self))
     def zip(self, cycled=False): return self._new((zip_cycle if cycled else zip)(*self))
     def zipwith(self, *rest, cycled=False): return self._new([self, *rest]).zip(cycled=cycled)
@@ -329,6 +345,8 @@ def product(self): return self.reduce(operator.mul)
          filter="Create new `L` filtered by predicate `f`, passing `args` and `kwargs` to `f`",
          argwhere="Like `filter`, but return indices for matching items",
          map="Create new `L` with `f` applied to all `items`, passing `args` and `kwargs` to `f`",
+         map_filter="Same as `map` with `f` followed by `filter` with `g`",
+         map_first="First element of `map_filter`",
          map_dict="Like `map`, but creates a dict from `items` to function results",
          starmap="Like `map`, but use `itertools.starmap`",
          itemgot="Create new `L` with item `idx` of all `items`",

fastcore/utils.py

@@ -3,7 +3,7 @@
 __all__ = ['ifnone', 'maybe_attr', 'basic_repr', 'get_class', 'mk_class', 'wrap_class', 'ignore_exceptions', 'dict2obj',
            'store_attr', 'attrdict', 'properties', 'camel2snake', 'snake2camel', 'class2attr', 'hasattrs', 'ShowPrint',
            'Int', 'Str', 'Float', 'tuplify', 'detuplify', 'replicate', 'uniqueify', 'setify', 'merge', 'is_listy',
-           'range_of', 'groupby', 'first', 'last_index', 'shufflish', 'IterLen', 'ReindexCollection', 'num_methods',
+           'range_of', 'groupby', 'last_index', 'shufflish', 'IterLen', 'ReindexCollection', 'num_methods',
            'rnum_methods', 'inum_methods', 'fastuple', 'Inf', 'in_', 'lt', 'gt', 'le', 'ge', 'eq', 'ne', 'add', 'sub',
            'mul', 'truediv', 'is_', 'is_not', 'in_', 'true', 'stop', 'gen', 'chunked', 'trace', 'compose', 'maps',
            'partialler', 'mapped', 'instantiate', 'using_attr', 'Self', 'Self', 'remove_patches_path', 'bunzip',
@@ -217,12 +217,6 @@ def groupby(x, key):
     for o in x: res.setdefault(key(o), []).append(o)
     return res
 
-# Cell
-def first(x):
-    "First element of `x`, or None if missing"
-    try: return next(iter(x))
-    except StopIteration: return None
-
 # Cell
 def last_index(x, o):
     "Finds the last index of occurence of `x` in `o` (returns -1 if no occurence)"