fix_build_docs_error

Author: SunsetWolf

qlib/data/dataset/handler.py

@@ -66,38 +66,41 @@ def fetch(
 
 class DataHandler(BaseDataHandler):
     """
-
     The motivation of DataHandler:
-    - it proivdes a implementation of BaseDataHandler that we implement it with
-      - Handle response with a internal loaded dataframe
-        - the dataframe is loaded by a data loader.
 
-    The steps to using a handler
-    1. initialized data handler  (call by `init`).
-    2. use the data.
+    This class provides an implementation of `BaseDataHandler` that:
+    - Handle response with a internal loaded dataframe
+    - The dataframe is loaded by a data loader.
+
+    Steps to use a handler:
+
+    1. Initialize the data handler by calling `init()`
+    2. Use the data via the handler interface
 
+    Index conventions:
 
-    The data handler try to maintain a handler with 2 level.
-    `datetime` & `instruments`.
+    The data handler maintains a handler with two levels of index:
+    - `datetime`
+    - `instruments`
 
-    Any order of the index level can be supported (The order will be implied in the data).
-    The order  <`datetime`, `instruments`> will be used when the dataframe index name is missed.
+    The order of index levels is flexible, and will be inferred from the data.
+    If the index name is missing, the default order `<datetime, instruments>` is assumed.
 
-    Example of the data:
-    The multi-index of the columns is optional.
+    Example of the data (with optional multi-index columns):
 
     .. code-block:: text
 
-                                feature                                                            label
-                                $close     $volume  Ref($close, 1)  Mean($close, 3)  $high-$low  LABEL0
+                                  feature                                                            label
+                                  $close     $volume  Ref($close, 1)  Mean($close, 3)  $high-$low  LABEL0
         datetime   instrument
         2010-01-04 SH600000    81.807068  17145150.0       83.737389        83.016739    2.741058  0.0032
                    SH600004    13.313329  11800983.0       13.313329        13.317701    0.183632  0.0042
                    SH600005    37.796539  12231662.0       38.258602        37.919757    0.970325  0.0289
 
+    Performance Tips:
 
-    Tips for improving the performance of datahandler
-    - Fetching data with `col_set=CS_RAW` will return the raw data and may avoid pandas from copying the data when calling `loc`
+    - Fetching data with `col_set=CS_RAW` returns raw data
+    - This may avoid unnecessary copying by pandas when calling `loc`
     """
 
     _data: pd.DataFrame  # underlying data.