Automated legend creation for 3D plot

I'm trying to update below function to report the clusters info via legend:

color_names = ["red", "blue", "yellow", "black", "pink", "purple", "orange"]

def plot_3d_transformed_data(df, title, colors="red"):
 
  ax = plt.figure(figsize=(12,10)).gca(projection='3d')
  #fig = plt.figure(figsize=(8, 8))
  #ax = fig.add_subplot(111, projection='3d')
  

  if type(colors) is np.ndarray:
    for cname, class_label in zip(color_names, np.unique(colors)):
      X_color = df[colors == class_label]
      ax.scatter(X_color[:, 0], X_color[:, 1], X_color[:, 2], marker="x", c=cname, label=f"Cluster {class_label}" if type(colors) is np.ndarray else None)
  else:
      ax.scatter(df.Type, df.Length, df.Freq, alpha=0.6, c=colors, marker="x", label=str(clusterSizes)  )

  ax.set_xlabel("PC1: Type")
  ax.set_ylabel("PC2: Length")
  ax.set_zlabel("PC3: Frequency")
  ax.set_title(title)
  
  if type(colors) is np.ndarray:
    #ax.legend()
    plt.gca().legend()
    
  
  plt.legend(bbox_to_anchor=(1.04,1), loc="upper left")
  plt.show()

So I call my function to visualize the clusters patterns by:

plot_3d_transformed_data(pdf_km_pred,
                         f'Clustering rare URL parameters for data of date: {DATE_FROM}  \nMethod: KMeans over PCA \nn_clusters={n_clusters} , Distance_Measure={DistanceMeasure}',
                         colors=pdf_km_pred.prediction_km)

print(clusterSizes)

Sadly I can't show the legend, and I have to print clusters members manually under the 3D plot. This is the output without legend with the following error: No handles with labels found to put in legend.

I check this post, but I couldn't figure out what is the mistake in function to pass the cluster label list properly. I want to update the function so that I can demonstrate cluster labels via clusterSizes.index and their scale via clusterSizes.size

Expected output: As here suggests better using legend_elements() to determine a useful number of legend entries to be shown and return a tuple of handles and labels automatically.

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