[Doc] Update links by :ref in dataset user guide (#2024)

* PPIDataset

* Revert "PPIDataset"

This reverts commit 264bd0c960cfa698a7bb946dad132bf52c2d0c8a.

* data pipeline user guide

* remove chapter numbers

* Update data.rst

* image in dataset userguide

* update links using ref

docs/source/api/python/dgl.data.rst

@@ -20,6 +20,8 @@ DGL builtin dataset
 .. autoclass:: DGLBuiltinDataset
     :members: download
 
+.. _sstdata:
+
 Stanford sentiment treebank dataset
 ```````````````````````````````````
 
@@ -28,6 +30,7 @@ For more information about the dataset, see `Sentiment Analysis <https://nlp.sta
 .. autoclass:: SSTDataset
     :members: __getitem__, __len__
 
+.. _karateclubdata:
 
 Karate club dataset
 ```````````````````````````````````
@@ -35,6 +38,7 @@ Karate club dataset
 .. autoclass:: KarateClubDataset
     :members: __getitem__, __len__
 
+.. _citationdata:
 
 Citation network dataset
 ```````````````````````````````````
@@ -48,6 +52,7 @@ Citation network dataset
 .. autoclass:: PubmedGraphDataset
     :members: __getitem__, __len__
 
+.. _kgdata:
 
 Knowlege graph dataset
 ```````````````````````````````````
@@ -61,6 +66,7 @@ Knowlege graph dataset
 .. autoclass:: WN18Dataset
     :members: __getitem__, __len__
 
+.. _rdfdata:
 
 RDF datasets
 ```````````````````````````````````
@@ -77,7 +83,7 @@ RDF datasets
 .. autoclass:: AMDataset
     :members: __getitem__, __len__
 
-
+.. _corafulldata:
 
 CoraFull dataset
 ```````````````````````````````````
@@ -85,6 +91,7 @@ CoraFull dataset
 .. autoclass:: CoraFullDataset
     :members: __getitem__, __len__
 
+.. _amazoncobuydata:
 
 Amazon Co-Purchase dataset
 ```````````````````````````````````
@@ -95,6 +102,7 @@ Amazon Co-Purchase dataset
 .. autoclass:: AmazonCoBuyPhotoDataset
     :members: __getitem__, __len__
 
+.. _coauthordata:
 
 Coauthor dataset
 ```````````````````````````````````
@@ -105,6 +113,7 @@ Coauthor dataset
 .. autoclass:: CoauthorPhysicsDataset
     :members: __getitem__, __len__
 
+.. _bitcoinotcdata:
 
 BitcoinOTC dataset
 ```````````````````````````````````
@@ -119,6 +128,7 @@ ICEWS18 dataset
 .. autoclass:: ICEWS18Dataset
     :members: __getitem__, __len__
 
+.. _qm7bdata:
 
 QM7b dataset
 ```````````````````````````````````
@@ -134,6 +144,7 @@ GDELT dataset
 .. autoclass:: GDELTDataset
     :members: __getitem__, __len__
 
+.. _minigcdataset:
 
 Mini graph classification dataset
 `````````````````````````````````
@@ -141,6 +152,8 @@ Mini graph classification dataset
 .. autoclass:: MiniGCDataset
     :members: __getitem__, __len__
 
+.. _tudata:
+
 TU dataset
 ``````````
 
@@ -150,6 +163,8 @@ TU dataset
 .. autoclass:: LegacyTUDataset
     :members: __getitem__, __len__
 
+.. _gindataset:
+
 Graph isomorphism network dataset
 ```````````````````````````````````
 
@@ -158,6 +173,7 @@ A compact subset of graph kernel dataset
 .. autoclass:: GINDataset
     :members: __getitem__, __len__
 
+.. _ppidata:
 
 Protein-Protein Interaction dataset
 ```````````````````````````````````
@@ -165,6 +181,7 @@ Protein-Protein Interaction dataset
 .. autoclass:: PPIDataset
     :members: __getitem__, __len__
 
+.. _redditdata:
 
 Reddit dataset
 ``````````````
@@ -172,6 +189,7 @@ Reddit dataset
 .. autoclass:: RedditDataset
     :members: __getitem__, __len__
 
+.. _sbmdata:
 
 Symmetric Stochastic Block Model Mixture dataset
 ````````````````````````````````````````````````

docs/source/guide/data.rst

@@ -2,8 +2,7 @@
 Graph data input pipeline in DGL
 ==================================
 
-DGL implements many commonly used graph datasets in
-`dgl.data <https://docs.dgl.ai/en/latest/api/python/dgl.data.html>`__. They
+DGL implements many commonly used graph datasets in :ref:`apidata`. They
 follow a standard pipeline defined in class :class:`dgl.data.DGLDataset`. We highly
 recommend processing graph data into a :class:`dgl.data.DGLDataset` subclass, as the
 pipeline provides simple and clean solution for loading, processing and
@@ -17,7 +16,7 @@ DGLDataset class
 --------------------
 
 :class:`dgl.data.DGLDataset` is the base class for processing, loading and saving
-graph datasets defined in ``dgl.data``. It implements the basic pipeline
+graph datasets defined in :ref:`apidata`. It implements the basic pipeline
 for processing graph data. The following flow chart shows how the
 pipeline works.
 
@@ -101,8 +100,7 @@ template of ``MyDataset`` is as follows.
 ``__getitem__(idx)`` and ``__len__()`` that must be implemented in the
 subclass. But we recommend to implement saving and loading as well,
 since they can save significant time for processing large datasets, and
-there are several APIs making it easy (see `Save and load data 
-<file:///Users/xiangkhu/Documents/GitHub/dgl/docs/build/html/guide/data.html#save-and-load-data>`__).
+there are several APIs making it easy (see :ref:`ref-save-load-data`).
 
 Note that the purpose of :class:`dgl.data.DGLDataset` is to provide a standard and
 convenient way to load graph data. We can store graphs, features,
@@ -287,13 +285,13 @@ in `Training Graph Classification models <https://>`__.
 For more examples of graph classification datasets, please refer to our builtin graph classification
 datasets: 
 
-* `GINDataset <https://docs.dgl.ai/en/latest/api/python/dgl.data.html#graph-isomorphism-network-dataset>`__
+* :ref:`gindataset`
 
-* `MiniGCDataset <https://docs.dgl.ai/en/latest/api/python/dgl.data.html#mini-graph-classification-dataset>`__
+* :ref:`minigcdataset`
 
-* `QM7bDataset <https://docs.dgl.ai/en/latest/api/python/dgl.data.html#qm7b-dataset>`__
+* :ref:`qm7bdata`
 
-* `TUDataset <https://docs.dgl.ai/en/latest/api/python/dgl.data.html#tu-dataset>`__
+* :ref:`tudata`
 
 Processing Node Classification datasets
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -389,25 +387,25 @@ A complete guide for training node classification models can be found in
 For more examples of node classification datasets, please refer to our
 builtin datasets:
 
-* `CitationGraphDataset <https://docs.dgl.ai/en/latest/api/python/dgl.data.html#citation-network-dataset>`__
+* :ref:`citationdata`
 
-* `CoraFullDataset <https://docs.dgl.ai/en/latest/api/python/dgl.data.html#corafull-dataset>`__
+* :ref:`corafulldata`
 
-* `Amazon Co-Purchase dataset <https://docs.dgl.ai/en/latest/api/python/dgl.data.html#amazon-co-purchase-dataset>`__
+* :ref:`amazoncobuydata`
 
-* `Coauthor dataset <https://docs.dgl.ai/en/latest/api/python/dgl.data.html#coauthor-dataset>`__
+* :ref:`coauthordata`
 
-* `KarateClubDataset <https://docs.dgl.ai/en/latest/api/python/dgl.data.html#karate-club-dataset>`__
+* :ref:`karateclubdata`
 
-* `PPIDataset <https://docs.dgl.ai/en/latest/api/python/dgl.data.html#protein-protein-interaction-dataset>`__
+* :ref:`ppidata`
 
-* `RedditDataset <https://docs.dgl.ai/en/latest/api/python/dgl.data.html#reddit-dataset>`__
+* :ref:`redditdata`
 
-* `SBMMixtureDataset <https://docs.dgl.ai/en/latest/api/python/dgl.data.html#symmetric-stochastic-block-model-mixture-dataset>`__
+* :ref:`sbmdata`
 
-* `SSTDataset <https://docs.dgl.ai/en/latest/api/python/dgl.data.html#stanford-sentiment-treebank-dataset>`__
+* :ref:`sstdata`
 
-* `RDF datasets <https://docs.dgl.ai/en/latest/api/python/dgl.data.html#rdf-datasets>`__
+* :ref:`rdfdata`
 
 Processing dataset for Link Prediction datasets
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -483,9 +481,11 @@ A complete guide for training link prediction models can be found in
 For more examples of link prediction datasets, please refer to our
 builtin datasets: 
 
-* `Knowlege graph dataset <https://docs.dgl.ai/en/latest/api/python/dgl.data.html#knowlege-graph-dataset>`__
+* :ref:`kgdata`
 
-* `BitcoinOTCDataset <https://docs.dgl.ai/en/latest/api/python/dgl.data.html#bitcoinotc-dataset>`__
+* :ref:`bitcoinotcdata`
+
+.. _ref-save-load-data:
 
 Save and load data
 ----------------------