Add data_access script

Author: adelavega

data_access.py

@@ -0,0 +1,35 @@
+# ### Accessing NeuroVault Archived Data
+
+# First, tar unzip the desired archive file:
+
+# +
+# #!tar -xvf november_2022.tar.gz
+# -
+
+# Next, we will load the files into pandas DataFrames:
+
+import pandas as pd
+
+# Load collections:
+
+collections = pd.read_csv('november_2022/statmaps_statisticmap.csv')
+
+collections.head()
+
+# Now, we load the statistical images, which require merging several tables.
+#
+# In order to merge `StatisticMap` to `Image`, we need the table `BaseStatisticMap`
+
+image = pd.read_csv('november_2022/statmaps_image.csv')
+basecollectionitem = pd.read_csv('november_2022/statmaps_basecollectionitem.csv')
+statisticmap = pd.read_csv('november_2022/statmaps_statisticmap.csv')
+
+# `image` table is first merged to `basecollectionitem` using `basecollectionitem_ptr_id`:
+
+image_merged = pd.merge(image, basecollectionitem, left_on='basecollectionitem_ptr_id', right_on='id')
+
+# Next, the `statisticmap` table can be merged to `image` using `image_ptr_id', which corresponds to 'basecollectionitem_ptr_id'
+
+statisticmap_merged = pd.merge(statisticmap, image_merged, left_on='image_ptr_id', right_on='basecollectionitem_ptr_id')
+
+statisticmap_merged.head()