How to get labels ids in Keras when training on multiple classes?
<p>I'm using <a href="http://keras.io/preprocessing/image/" rel="noreferrer"><code>flow_from_directory</code></a> to get the training set from a folder with the following structure:</p>

<pre><code>train
  class1
  class2
  class3
  ...
</code></pre>

<p>The generator is called as it follows:</p>

<pre><code>train_generator = train_datagen.flow_from_directory( 
        train_data_dir,                              
        target_size=(img_height, img_width),         
        batch_size=32,                               
        class_mode='categorical')  
</code></pre>

<p>I am not setting the argument <code>classes</code>, but I was expecting to get the labels in alphabetical order.</p>

<blockquote>
  <p><strong>classes</strong>: optional list of class subdirectories (e.g. <code>['dogs', 'cats']</code>). Default: None. If not provided, the list of classes will be automatically inferred (and the order of the classes, which will map to the label indices, will be alphanumeric).</p>
</blockquote>

<p>However, when I classify the training images (for checking which labels are being returned), I'm don't get any specific ordering. The training goes well (accuracy of ~85%), and there is a consistency with the output labels when classifying images from the same class.</p>

<p>How can I infer the labels numbers generated by <code>flow_from_directory</code> and map them to the classes?</p>