text reader support

LanguageBindings/Python/cntk/reader.py

@@ -20,10 +20,9 @@ def __eq__(self, x): return x is self
 
     def __ne__(self, x): return x is not self
 
-
 class UCIFastReader(AbstractReader):
 
-    """This is the reader class
+    """This is the reader class the maps to UCIFastReader of CNTK
     :param filename: data file path
     :param labels_node_name: the name of the labels node in the network
     :param labels_dim: number of label columns
@@ -65,7 +64,7 @@ def add_input(self, name_or_node, input_start, input_dim):
         :param input_dim: the number of columns
         """
         if not name_or_node or input_start is None or input_dim is None:
-            raise ValueError("one of the parameters of add_input is None or empty string") 
+            raise ValueError("one of the parameters of add_input is None") 
 
         self.inputs_def.append((name_or_node, input_start, input_dim))
 
@@ -108,10 +107,74 @@ def generate_config(self):
 
         return template % self
 
+class CNTKTextFormatReader(AbstractReader):
+
+    """This is the reader class the maps to CNTKTextFormatReader of CNTK
+    :param filename: data file path
+    :param inputs_def: is a list of tuples (name_or_node, alias, input_dim, format)
+        name_or_node: the name of the input in the network definition or the node itself
+        alias: a short name for the input, it is how inputs are referenced in the data files
+        input_dim: the lenght of the input vector
+        format: dense or sparse
+    """
+
+    def __init__(self, filename,
+                 inputs_def=None):
+        """ Reader constructor    
+        """
+        self["ReaderType"] = self.__class__.__name__
+        self["FileName"] = filename
+        self.inputs_def = inputs_def or []
+
+    def add_input(self, name_or_node, alias, input_dim, format="Dense"):
+        """Add an input to the reader
+        name_or_node: the name of the input in the network definition or the node itself
+        alias: a short name for the input, it is how inputs are referenced in the data files
+        input_dim: the lenght of the input vector
+        format: dense or sparse
+        """
+        if not name_or_node or input_dim is None or format is None:
+            raise ValueError("one of the parameters of add_input is None") 
+
+        alias = alias or name_or_node
+
+        self.inputs_def.append((name_or_node, alias, input_dim, format))
+
+    def generate_config(self):
+        """Generate the reader configuration block
+        """
+        template = '''
+            readerType = "%(ReaderType)s"
+            file = "%(FileName)s"                
+            '''
+
+        if self.inputs_def is not None:
+            template += '''
+            input = [
+            '''
+
+            for (name_or_node, alias, dim, format) in self.inputs_def:                
+                if (isinstance(name_or_node, ComputationNode)):
+                    name = name_or_node.var_name
+                    a = name_or_node.var_name
+                else:
+                    name = name_or_node
+                    a = alias
+                template += '''
+                {0}=[
+                    alias = "{1}"                
+                    dim = {2}		          
+                    format = "{3}"
+                ]'''.format(name, a, dim, format)
+
+            template += '''
+            ]
+            '''
+        return template % self
 
 def NumPyReader(data, filename):
     """
-    This is a convenience function that wraps Python arrays.
+    This is a factory that wraps Python arrays with a UCIFastReader.
     """
 
     import numpy as np