Merge pull request #1558 from reyoung/add_comments_to_v2_module

(Partially) Complete V2 Documentation

doc/api/index_cn.rst

@@ -1,2 +1,26 @@
 API
 ===
+
+模型配置 API
+------------
+
+..  toctree::
+    :maxdepth: 1
+
+    v2/model_configs.rst
+
+数据 API
+--------
+
+..  toctree::
+    :maxdepth: 1
+
+    v2/data.rst
+
+训练 API
+--------
+
+..	toctree::
+	:maxdepth: 1
+
+	v2/run_logic.rst

doc/api/index_en.rst

@@ -8,3 +8,19 @@ Model Config API
     :maxdepth: 1
 
     v2/model_configs.rst
+
+Data API
+--------
+
+..  toctree::
+    :maxdepth: 1
+
+    v2/data.rst
+
+Train API
+---------
+
+..	toctree::
+	:maxdepth: 1
+
+	v2/run_logic.rst

doc/api/v2/data.rst

@@ -0,0 +1,93 @@
+================
+Data Related API
+================
+
+
+#########
+DataTypes
+#########
+
+..  automodule:: paddle.v2.data_type
+    :members:
+
+##########
+DataFeeder
+##########
+
+..  automodule:: paddle.v2.data_feeder
+    :members:
+
+######
+Reader
+######
+
+..  automodule:: paddle.v2.reader
+    :members:
+
+..  automodule:: paddle.v2.reader.creator
+    :members:
+
+#########
+minibatch
+#########
+
+..  automodule:: paddle.v2.minibatch
+    :members:
+
+#######
+Dataset
+#######
+
+..  automodule:: paddle.v2.dataset
+    :members:
+
+
+mnist
++++++
+
+..  automodule:: paddle.v2.dataset.mnist
+    :members:
+
+
+cifar
++++++
+
+..  automodule:: paddle.v2.dataset.cifar
+    :members:
+
+conll05
++++++++
+
+..  automodule:: paddle.v2.dataset.conll05
+    :members:
+
+imdb
+++++
+
+..  automodule:: paddle.v2.dataset.imdb
+    :members:
+
+imikolov
+++++++++
+
+..  automodule:: paddle.v2.dataset.imikolov
+    :members:
+
+movielens
++++++++++
+
+..  automodule:: paddle.v2.dataset.movielens
+    :members:
+
+sentiment
++++++++++
+
+..  automodule:: paddle.v2.dataset.sentiment
+    :members:
+
+uci_housing
++++++++++++
+
+..  automodule:: paddle.v2.dataset.uci_housing
+    :members:
+

doc/api/v2/model_configs.rst

@@ -1,3 +1,7 @@
+#########################
+Configuration Related API
+#########################
+
 ======
 Layers
 ======
@@ -33,3 +37,10 @@ Networks
 
 ..	automodule:: paddle.v2.networks
 	:members:
+
+==========
+Optimizers
+==========
+
+..	automodule:: paddle.v2.optimizer
+	:members:

doc/api/v2/run_logic.rst

@@ -0,0 +1,26 @@
+###########
+Trainer API
+###########
+
+==========
+Parameters
+==========
+
+..  automodule:: paddle.v2.parameters
+    :members:
+
+
+=======
+Trainer
+=======
+
+..	automodule:: paddle.v2.trainer
+	:members:
+
+
+=====
+Event
+=====
+
+..	automodule:: paddle.v2.event
+	:members:

doc/design/reader/README.md

@@ -31,7 +31,7 @@ def reader_creator_random_image(width, height):
 
 An example implementation for multiple item data reader creator:
 ```python
-def reader_creator_random_imageand_label(widht, height, label):
+def reader_creator_random_image_and_label(width, height, label):
     def reader():
         while True:
             yield numpy.random.uniform(-1, 1, size=width*height), label

python/paddle/trainer/PyDataProvider2.py

@@ -45,6 +45,23 @@ class CacheType(object):
 
 
 class InputType(object):
+    """
+    InputType is the base class for paddle input types.
+
+    ..  note::
+
+        this is a base class, and should never be used by user.
+
+    :param dim: dimension of input. If the input is an integer, it means the
+                value range. Otherwise, it means the size of layer.
+    :type dim: int
+    :param seq_type: sequence type of input. 0 means it is not a sequence. 1
+                     means it is a variable length sequence. 2 means it is a
+                     nested sequence.
+    :type seq_type: int
+    :param type: data type of input.
+    :type type: int
+    """
     __slots__ = ['dim', 'seq_type', 'type']
 
     def __init__(self, dim, seq_type, tp):
@@ -54,20 +71,61 @@ class InputType(object):
 
 
 def dense_slot(dim, seq_type=SequenceType.NO_SEQUENCE):
+    """
+    Dense Vector. It means the input feature is dense float vector. For example,
+    if the input is an image with 28*28 pixels, the input of Paddle neural
+    network should be a dense vector with dimension 784.
+
+    :param dim: dimension of this vector.
+    :type dim: int
+    :param seq_type: sequence type of input.
+    :type seq_type: int
+    :return: An input type object.
+    :rtype: InputType
+    """
     return InputType(dim, seq_type, DataType.Dense)
 
 
 def sparse_non_value_slot(dim, seq_type=SequenceType.NO_SEQUENCE):
+    """
+    Sparse binary vector. It means the input feature is a sparse vector and the
+    every element in this vector is either zero or one.
+
+    :param dim: dimension of this vector.
+    :type dim: int
+    :param seq_type: sequence type of this input.
+    :type seq_type: int
+    :return: An input type object.
+    :rtype: InputType
+    """
     return InputType(dim, seq_type, DataType.SparseNonValue)
 
 
 def sparse_value_slot(dim, seq_type=SequenceType.NO_SEQUENCE):
+    """
+    Sparse vector. It means the input feature is a sparse vector. Most of the
+    elements in this vector are zero, others could be any float value.
+
+    :param dim: dimension of this vector.
+    :type dim: int
+    :param seq_type: sequence type of this input.
+    :type seq_type: int
+    :return: An input type object.
+    :rtype: InputType
+    """
     return InputType(dim, seq_type, DataType.SparseValue)
 
 
 def index_slot(value_range, seq_type=SequenceType.NO_SEQUENCE):
-    """Data type of integer.
+    """
+    Data type of integer.
+
+    :param seq_type: sequence type of this input.
+    :type seq_type: int
     :param value_range: range of this integer.
+    :type value_range: int
+    :return: An input type object
+    :rtype: InputType
     """
     return InputType(value_range, seq_type, DataType.Index)
 
@@ -76,10 +134,17 @@ dense_vector = dense_slot
 sparse_binary_vector = sparse_non_value_slot
 sparse_vector = sparse_value_slot
 integer_value = index_slot
-integer_value.__doc__ = index_slot.__doc__
 
 
 def dense_vector_sequence(dim):
+    """
+    Data type of a sequence of dense vector.
+
+    :param dim: dimension of dense vector.
+    :type dim: int
+    :return: An input type object
+    :rtype: InputType
+    """
     return dense_vector(dim, seq_type=SequenceType.SEQUENCE)
 
 
@@ -88,6 +153,15 @@ def dense_vector_sub_sequence(dim):
 
 
 def sparse_binary_vector_sequence(dim):
+    """
+    Data type of a sequence of sparse vector, which every element is either zero
+     or one.
+
+    :param dim: dimension of sparse vector.
+    :type dim: int
+    :return: An input type object
+    :rtype: InputType
+    """
     return sparse_binary_vector(dim, seq_type=SequenceType.SEQUENCE)
 
 
@@ -96,6 +170,15 @@ def sparse_binary_vector_sub_sequence(dim):
 
 
 def sparse_vector_sequence(dim):
+    """
+    Data type of a sequence of sparse vector, which most elements are zero,
+    others could be any float value.
+
+    :param dim: dimension of sparse vector.
+    :type dim: int
+    :return: An input type object
+    :rtype: InputType
+    """
     return sparse_vector(dim, seq_type=SequenceType.SEQUENCE)
 
 
@@ -104,8 +187,11 @@ def sparse_vector_sub_sequence(dim):
 
 
 def integer_value_sequence(value_range):
-    """Data type of a sequence of integer.
+    """
+    Data type of a sequence of integer.
+
     :param value_range: range of each element.
+    :type value_range: int
     """
     return integer_value(value_range, seq_type=SequenceType.SEQUENCE)
 
@@ -115,7 +201,6 @@ def integer_value_sub_sequence(dim):
 
 
 integer_sequence = integer_value_sequence
-integer_sequence.__doc__ = integer_value_sequence.__doc__
 
 
 class SingleSlotWrapper(object):

python/paddle/v2/data_feeder.py

@@ -12,8 +12,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from py_paddle import swig_paddle
 from py_paddle import DataProviderConverter
+
 import data_type
 
 __all__ = ['DataFeeder']
@@ -30,6 +30,9 @@ class DataFeeder(DataProviderConverter):
     
     The example usage:
 
+
+    ..  code-block:: python
+
         data_types = [('image', paddle.data_type.dense_vector(784)),
                       ('label', paddle.data_type.integer_value(10))]
         reader_dict = {'image':0, 'label':1}
@@ -43,20 +46,24 @@ class DataFeeder(DataProviderConverter):
         #                       [ [1.0,2.0,3.0,4.0], 5, [6,7,8] ]   # second sample
         #                     ]
         arg = feeder(minibatch_data)
-    """
 
-    def __init__(self, data_types, reader_dict):
+    ..  note::
-        """
+
+        This module is for internal use only. Users should use the `reader`
+        interface.
+
+
+
     :param data_types: A list to specify data name and type. Each item is
-                           a tuple of (data_name, data_type). For example:
+                       a tuple of (data_name, data_type).
-                           [('image', paddle.data_type.dense_vector(784)),
-                            ('label', paddle.data_type.integer_value(10))]
 
-        :type data_types: A list of tuple
+    :type data_types: list
     :param reader_dict: A dictionary to specify the position of each data
                         in the input data.
-        :type reader_dict: dict()
+    :type reader_dict: dict
     """
+
+    def __init__(self, data_types, reader_dict):
         self.input_names = []
         input_types = []
         self.reader_dict = reader_dict
@@ -70,22 +77,12 @@ class DataFeeder(DataProviderConverter):
         """
         :param dat: A list of mini-batch data. Each sample is a list or tuple
                     one feature or multiple features.
-                    for example:
-                    [ 
-                      ([0.2, 0.2], ), # first sample
-                      ([0.8, 0.3], ), # second sample
-                    ]
-                    or,
-                    [ 
-                      [[0.2, 0.2], ], # first sample
-                      [[0.8, 0.3], ], # second sample
-                    ]
 
-        :type dat: List
+        :type dat: list
         :param argument: An Arguments object contains this mini-batch data with
                          one or multiple features. The Arguments definition is
                          in the API.
-        :type argument: swig_paddle.Arguments
+        :type argument: py_paddle.swig_paddle.Arguments
         """
 
         def reorder_data(data):

python/paddle/v2/data_type.py

@@ -12,11 +12,15 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from paddle.trainer.PyDataProvider2 import \
+import paddle.trainer.PyDataProvider2 as pydp2
-    InputType, DataType, dense_vector, sparse_binary_vector,\
-    sparse_vector, integer_value, integer_value_sequence
 
-__all__ = [
+import_list = [
-    'InputType', 'DataType', 'dense_vector', 'sparse_binary_vector',
+    nm for nm in dir(pydp2)
-    'sparse_vector', 'integer_value', 'integer_value_sequence'
+    if '_' in nm and nm[0] != '_' and ('value' in nm or 'vector' in nm)
 ]
+import_list.extend(['InputType'])
+
+for nm in import_list:
+    globals()[nm] = getattr(pydp2, nm)
+
+__all__ = import_list

python/paddle/v2/dataset/__init__.py

@@ -11,6 +11,9 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
+"""
+Dataset package.
+"""
 
 import mnist
 import imikolov

python/paddle/v2/dataset/cifar.py

@@ -13,6 +13,8 @@
 # limitations under the License.
 """
 CIFAR dataset: https://www.cs.toronto.edu/~kriz/cifar.html
+
+TODO(yuyang18): Complete the comments.
 """
 
 import cPickle

python/paddle/v2/dataset/conll05.py

@@ -16,15 +16,17 @@ import tarfile
 import gzip
 import itertools
 from common import download
-
-__all__ = ['test, get_dict', 'get_embedding']
 """
 Conll 2005 dataset.  Paddle semantic role labeling Book and demo use this
 dataset as an example. Because Conll 2005 is not free in public, the default
 downloaded URL is test set of Conll 2005 (which is public). Users can change
 URL and MD5 to their Conll dataset.
+
+TODO(yuyang18): Complete comments.
 """
 
+__all__ = ['test, get_dict', 'get_embedding']
+
 DATA_URL = 'http://www.cs.upc.edu/~srlconll/conll05st-tests.tar.gz'
 DATA_MD5 = '387719152ae52d60422c016e92a742fc'
 WORDDICT_URL = 'http://paddlepaddle.bj.bcebos.com/demo/srl_dict_and_embedding/wordDict.txt'

python/paddle/v2/dataset/imdb.py

@@ -13,6 +13,8 @@
 # limitations under the License.
 """
 IMDB dataset: http://ai.stanford.edu/%7Eamaas/data/sentiment/aclImdb_v1.tar.gz
+
+TODO(yuyang18): Complete comments.
 """
 
 import paddle.v2.dataset.common

python/paddle/v2/dataset/imikolov.py

@@ -13,6 +13,8 @@
 # limitations under the License.
 """
 imikolov's simple dataset: http://www.fit.vutbr.cz/~imikolov/rnnlm/
+
+Complete comments.
 """
 import paddle.v2.dataset.common
 import tarfile

python/paddle/v2/dataset/mnist.py

@@ -13,6 +13,9 @@
 # limitations under the License.
 """
 MNIST dataset.
+
+This module will download dataset from http://yann.lecun.com/exdb/mnist/ and
+parse train set and test set into paddle reader creators.
 """
 import paddle.v2.dataset.common
 import subprocess
@@ -72,6 +75,15 @@ def reader_creator(image_filename, label_filename, buffer_size):
 
 
 def train():
+    """
+    MNIST train set creator.
+
+    It returns a reader creator, each sample in the reader is image pixels in
+    [0, 1] and label in [0, 9].
+
+    :return: Train reader creator
+    :rtype: callable
+    """
     return reader_creator(
         paddle.v2.dataset.common.download(TRAIN_IMAGE_URL, 'mnist',
                                           TRAIN_IMAGE_MD5),
@@ -80,6 +92,15 @@ def train():
 
 
 def test():
+    """
+    MNIST test set cretor.
+
+    It returns a reader creator, each sample in the reader is image pixels in
+    [0, 1] and label in [0, 9].
+
+    :return: Test reader creator.
+    :rtype: callable
+    """
     return reader_creator(
         paddle.v2.dataset.common.download(TEST_IMAGE_URL, 'mnist',
                                           TEST_IMAGE_MD5),

python/paddle/v2/dataset/movielens.py

@@ -11,6 +11,11 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
+"""
+Movielens 1-M dataset.
+
+TODO(yuyang18): Complete comments.
+"""
 
 import zipfile
 from common import download

python/paddle/v2/dataset/sentiment.py

@@ -15,18 +15,19 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 """
-The script fetch and preprocess movie_reviews data set
+The script fetch and preprocess movie_reviews data set that provided by NLTK
 
-that provided by NLTK
+TODO(yuyang18): Complete dataset.
 """
 
-import common
 import collections
-import nltk
-import numpy as np
 from itertools import chain
+
+import nltk
 from nltk.corpus import movie_reviews
 
+import common
+
 __all__ = ['train', 'test', 'get_word_dict']
 NUM_TRAINING_INSTANCES = 1600
 NUM_TOTAL_INSTANCES = 2000

python/paddle/v2/dataset/uci_housing.py

@@ -11,6 +11,11 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
+"""
+UCI Housing dataset.
+
+TODO(yuyang18): Complete comments.
+"""
 
 import numpy as np
 import os

python/paddle/v2/event.py

@@ -34,6 +34,10 @@ class WithMetric(object):
 
 
 class TestResult(WithMetric):
+    """
+    Result that trainer.test return.
+    """
+
     def __init__(self, evaluator, cost):
         super(TestResult, self).__init__(evaluator)
         self.cost = cost

python/paddle/v2/minibatch.py

@@ -12,24 +12,30 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+__all__ = ['batch']
+
 
 def batch(reader, batch_size):
     """
-    Create a batch reader.
+    Create a batched reader.
+
     :param reader: the data reader to read from.
-    :param batch_size: batch_size
+    :type reader: callable
-    :return: the batch reader.
+    :param batch_size: size of each mini-batch
+    :type batch_size: int
+    :return: the batched reader.
+    :rtype: callable
     """
 
     def batch_reader():
         r = reader()
-        batch = []
+        b = []
         for instance in r:
-            batch.append(instance)
+            b.append(instance)
-            if len(batch) == batch_size:
+            if len(b) == batch_size:
-                yield batch
+                yield b
-                batch = []
+                b = []
-        if batch:
+        if b:
-            yield batch
+            yield b
 
     return batch_reader

python/paddle/v2/optimizer.py

@@ -1,7 +1,12 @@
 import py_paddle.swig_paddle as swig_api
-import paddle.trainer_config_helpers.optimizers as v1_optimizers
+
 import paddle.trainer_config_helpers.config_parser_utils as config_parser_utils
-import paddle.v2
+import paddle.trainer_config_helpers.optimizers as v1_optimizers
+"""
+Optimizers(update equation) for SGD method.
+
+TODO(yuyang18): Complete comments.
+"""
 
 __all__ = [
     'Momentum', 'Adam', 'Adamax', 'AdaGrad', 'DecayedAdaGrad', 'AdaDelta',
@@ -44,7 +49,7 @@ class Optimizer(object):
 class Momentum(Optimizer):
     def __init__(self, momentum=None, sparse=False, **kwargs):
         learning_method = v1_optimizers.MomentumOptimizer(
-            momentum=None, sparse=False)
+            momentum=momentum, sparse=sparse)
         super(Momentum, self).__init__(
             learning_method=learning_method, **kwargs)
 

python/paddle/v2/parameters.py

@@ -10,6 +10,7 @@ __all__ = ['Parameters', 'create']
 def create(layers):
     """
     Create parameter pool by topology.
+
     :param layers:
     :return:
     """
@@ -67,6 +68,7 @@ class Parameters(object):
     def keys(self):
         """
         keys are the names of each parameter.
+
         :return: list of parameter name
         :rtype: list
         """
@@ -75,6 +77,7 @@ class Parameters(object):
     def names(self):
         """
         names of each parameter.
+
         :return: list of parameter name
         :rtype: list
         """
@@ -83,6 +86,7 @@ class Parameters(object):
     def has_key(self, key):
         """
         has_key return true if there are such parameter name == key
+
         :param key: Parameter name
         :type key: basestring
         :return: True if contains such key
@@ -136,6 +140,7 @@ class Parameters(object):
     def get_shape(self, key):
         """
         get shape of the parameter.
+
         :param key: parameter name
         :type key: basestring
         :return: parameter's shape
@@ -190,6 +195,7 @@ class Parameters(object):
     def set(self, parameter_name, value):
         """
         Set parameter by parameter name & matrix.
+
         :param parameter_name: parameter name
         :type parameter_name: basestring
         :param value: parameter matrix

python/paddle/v2/reader/__init__.py

@@ -11,15 +11,64 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
+"""
+At training and testing time, PaddlePaddle programs need to read data. To ease
+the users' work to write data reading code, we define that
 
-# It would be too lengthy to require our users to prefix decorators with `decorator`.
+- A *reader* is a function that reads data (from file, network, random number
-# For example, we want the following line
+  generator, etc) and yields data items.
-#
+- A *reader creator* is a function that returns a reader function.
-#     r = paddle.reader.decorator.bufferd(paddle.reader.creator.text("hello.txt"))
+- A *reader decorator* is a function, which accepts one or more readers, and
-#
+  returns a reader.
-# to be a shorter version:
+- A *batch reader* is a function that reads data (from *reader*, file, network,
-#
+  random number generator, etc) and yields a batch of data items.
-#     r = paddle.reader.buffered(paddle.reader.creator.text("hello.txt"))
+
+#####################
+Data Reader Interface
+#####################
+
+Indeed, *data reader* doesn't have to be a function that reads and yields data
+items. It can be any function with no parameter that creates a iterable
+(anything can be used in :code:`for x in iterable`)\:
+
+..  code-block:: python
+
+    iterable = data_reader()
+
+Element produced from the iterable should be a **single** entry of data,
+**not** a mini batch. That entry of data could be a single item, or a tuple of
+items.
+Item should be of `supported type <http://www.paddlepaddle.org/doc/ui/data_provider
+/pydataprovider2.html?highlight=dense_vector#input-types>`_ (e.g., numpy 1d
+array of float32, int, list of int)
+
+An example implementation for single item data reader creator:
+
+..  code-block:: python
+
+    def reader_creator_random_image(width, height):
+        def reader():
+            while True:
+                yield numpy.random.uniform(-1, 1, size=width*height)
+    return reader
+
+An example implementation for multiple item data reader creator:
+
+..  code-block:: python
+
+    def reader_creator_random_image_and_label(width, height, label):
+        def reader():
+            while True:
+                yield numpy.random.uniform(-1, 1, size=width*height), label
+    return reader
+
+
+TODO(yuyang18): Should we add whole design doc here?
+"""
+
+import decorator
 from decorator import *
 
 import creator
+
+__all__ = decorator.__all__ + ['creator']

python/paddle/v2/reader/creator.py

@@ -11,6 +11,10 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
+"""
+Creator package contains some simple reader creator, which could be used in user
+program.
+"""
 
 __all__ = ['np_array', 'text_file']
 
@@ -38,7 +42,7 @@ def np_array(x):
 def text_file(path):
     """
     Creates a data reader that outputs text line by line from given text file.
-    Trailing new line ('\n') of each line will be removed.
+    Trailing new line ('\\\\n') of each line will be removed.
 
     :path: path of the text file.
     :returns: data reader of text file

python/paddle/v2/reader/decorator.py

@@ -28,9 +28,11 @@ def map_readers(func, *readers):
     Creates a data reader that outputs return value of function using
     output of each data readers as arguments.
 
-    :param func: function to use.
+    :param func: function to use. The type of func should be (Sample) => Sample
-    :param *readers: readers whose outputs will be used as arguments of func.
+    :type: callable
-    :returns: the created data reader.
+    :param readers: readers whose outputs will be used as arguments of func.
+    :return: the created data reader.
+    :rtype: callable
     """
 
     def reader():
@@ -45,16 +47,19 @@ def map_readers(func, *readers):
 
 def shuffle(reader, buf_size):
     """
-    Creates a data reader whose data output is suffled.
+    Creates a data reader whose data output is shuffled.
 
     Output from the iterator that created by original reader will be
     buffered into shuffle buffer, and then shuffled. The size of shuffle buffer
     is determined by argument buf_size.
 
     :param reader: the original reader whose output will be shuffled.
+    :type reader: callable
     :param buf_size: shuffle buffer size.
+    :type buf_size: int
 
-    :returns:the new reader whose output is shuffled.
+    :return: the new reader whose output is shuffled.
+    :rtype: callable
     """
 
     def data_reader():
@@ -88,7 +93,8 @@ def chain(*readers):
     [0, 0, 0, 1, 1, 1, 2, 2, 2]
 
     :param readers: input readers.
-    :returns: the new data reader.
+    :return: the new data reader.
+    :rtype: callable
     """
 
     def reader():
@@ -115,12 +121,13 @@ def compose(*readers, **kwargs):
     The composed reader will output:
     (1, 2, 3, 4, 5)
 
-    :*readers: readers that will be composed together.
+    :param readers: readers that will be composed together.
-    :check_alignment: if True, will check if input readers are aligned
+    :param check_alignment: if True, will check if input readers are aligned
         correctly. If False, will not check alignment and trailing outputs
         will be discarded. Defaults to True.
+    :type check_alignment: bool
 
-    :returns: the new data reader.
+    :return: the new data reader.
 
     :raises ComposeNotAligned: outputs of readers are not aligned.
         Will not raise when check_alignment is set to False.
@@ -161,7 +168,9 @@ def buffered(reader, size):
     as the buffer is not empty.
     
     :param reader: the data reader to read from.
+    :type reader: callable
     :param size: max buffer size.
+    :type size: int
     
     :returns: the buffered data reader.
     """
@@ -196,6 +205,13 @@ def buffered(reader, size):
 def firstn(reader, n):
     """
     Limit the max number of samples that reader could return.
+
+    :param reader: the data reader to read from.
+    :type reader: callable
+    :param n: the max number of samples that return.
+    :type n: int
+    :return: the decorated reader.
+    :rtype: callable
     """
 
     # TODO(yuyang18): Check if just drop the reader, could clean the opened