removed nested columns

easier analysis of fields, also fix url_64kb to include full path

README.md

@@ -89,42 +89,34 @@ task_categories:
 pretty_name: LibriVox Tracks
 dataset_info:
   features:
-  - name: book
-    struct:
-    - name: id
-      dtype: string
-    - name: title
-      dtype: string
   - name: language
     dtype: string
   - name: text
     dtype: string
-  - name: section
-    struct:
-    - name: id
-      dtype: string
-    - name: num
-      dtype: string
-    - name: title
-      dtype: string
   - name: url
     dtype: string
-  - name: reader
-    struct:
-    - name: reader_id
-      dtype: string
-    - name: display_name
-      dtype: string
   - name: duration
     dtype: float64
   - name: url_64kb
     dtype: string
+  - name: book_id
+    dtype: int32
+  - name: section_id
+    dtype: int32
+  - name: reader_id
+    dtype: int32
+  - name: book_title
+    dtype: string
+  - name: section_title
+    dtype: string
+  - name: reader_name
+    dtype: string
   splits:
   - name: train
-    num_bytes: 120918187
+    num_bytes: 112633531
     num_examples: 410709
-  download_size: 23401108
-  dataset_size: 120918187
+  download_size: 22317177
+  dataset_size: 112633531
 configs:
 - config_name: default
   data_files:

data/train-00000-of-00002.parquet

@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:03f556dd99cd2502b5f257ba8a8156100dc73103f9ece6ed18a0a4152f1556ff
-size 12241729
+oid sha256:76d3ab6743c4d6457c83c02fbb1895ec3c73db2fe09417604a9e8b2b7aced121
+size 11713542

data/train-00001-of-00002.parquet

@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:0bae6d0454c36aa985d8727d3715d797b586eb83ea7cb7e74425f1291f6c3be8
-size 11159379
+oid sha256:84fa3e7fc39272772da0a92109b804fcf4fa729ca193d021ecebcf33532f76b0
+size 10603635