Add basic transformers

1 files changed, 25 insertions, 0 deletions

diff --git a/transformers.py b/transformers.py
new file mode 100644
index 0000000..2a49a11
--- /dev/null
+++ b/transformers.py
@@ -0,0 +1,25 @@
+from fuel.transformers import Transformer, Filter, Mapping
+
+class Select(Transformer):
+    def __init__(self, data_stream, sources):
+        super(Select, self).__init__(data_stream)
+        self.ids = [data_stream.sources.index(source) for source in sources]
+        self.sources=sources
+
+    def get_data(self, request=None):
+        if request is not None:
+            raise ValueError
+        data=next(self.child_epoch_iterator)
+        return [data[id] for id in self.ids]
+
+def add_extremities(stream, k):
+    id_polyline=stream.sources.index('polyline')
+    def extremities(x):
+        return (x[id_polyline][:k], x[id_polyline][-k:])
+    stream = Filter(stream, lambda x: len(x[id_polyline])>=k)
+    stream = Mapping(stream, extremeties, ('first_k', 'last_k'))
+    return stream
+
+def add_destination(stream):
+    id_polyline=stream.sources.index('polyline')
+    return Mapping(stream, lambda x: x[id_polyline][-1], ('destination',))