clarify dataset structure, adding in parquet files

README.md

@@ -130,11 +130,6 @@ Leaderboard is available on the [Codabench Challenge page](https://www.codabench
 
 ```
 /dataset/
-    flatten_images/
-        <img_id 1>.png
-        <img_id 2>.png
-        ...
-        <img_id n>.png
     color_and_scale_images/
         colorpicker_<colorpicker_id 1>.png
         colorpicker_<colorpicker_id 2>.png
@@ -144,6 +139,19 @@ Leaderboard is available on the [Codabench Challenge page](https://www.codabench
         scalebar_<scalebarid 2>.png
         ...
         scalebar_<scalebarid k>.png
+    data/
+        train-00000-of-00029.parquet
+        train-00001-of-00029.parquet
+        ...
+        train-00028-of-00029.parquet
+        validation-00000-of-00004.parquet
+        ...
+        validation-00003-of-00004.parquet
+    flattened_images/
+        <img_id 1>.png
+        <img_id 2>.png
+        ...
+        <img_id n>.png
     train.csv
     val.csv
 ```
@@ -156,6 +164,8 @@ Metadata include an identifier for a collection event (`eventID`), the date of t
 
 The `train.csv` and `val.csv` files are to be used for training models for submission and reflect the information that will be given during testing sans `siteID`, `collectDate`, and the target variables `SPEI_30d`, `SPEI_1y`, and `SPEI_2y`. Please see the [challenge sample repository](https://github.com/Imageomics/HDR-SMood-Challenge-sample) for an example of how these were used in training the baseline submission.
 
+The `data/` folder contains the dataset in parquet format, where `train` prefix indicates it corresponds to the images and metadata in `train.csv`, while `validation` corresponds to `val.csv`. These are rendered by the dataset viewer.
+
 ### Data Fields
 
 Both `train.csv` and `val.csv` have the following columns.