title: how to Split data in 3 folds (train,validation,test) using ImageDataGenerator when data is in different directories of each class
body: <p>How do I split my data into 3 folds using <code>ImageDataGenerator</code> of Keras? <code>ImageDataGenerator</code> only gives <code>validation_split</code> argument so if I use it, I wont be having my test set for later purpose. </p>
  
  <p>My data is in the form of</p>
  
  <pre><code>&gt;input_data_dir
   &gt;class_1_dir
    &gt; image_1.png
    &gt; image_2.png
   &gt; class_2_dir
   &gt; class_3_dir
  </code></pre>