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visualkeras for Keras / TensorFlow

Introduction

Visualkeras is a Python package to help visualize Keras (either standalone or included in tensorflow) neural network architectures. It allows easy styling to fit most needs. This module supports layered style architecture generation which is great for CNNs (Convolutional Neural Networks), and a graph style architecture, which works great for most models including plain feed-forward networks. For help in citing this project, refer here.

Model Support

Mode	Sequential	Functional	Subclassed models
`visualkeras.layered_view()`	yes<sup>(1)</sup>	partially<sup>(1,2)</sup>	not tested
`visualkeras.graph_view()`	yes	yes	not tested

<sup>1</sup>: Any tensor with more than 3 dimensions will be rendered as 3D tensor with elongated z-axis.

<sup>2</sup>: Only linear models where each layer has no more than one in or output. Non-linear models will be shown in sequential order.

Version Support

We currently only support Keras versions 2 and above. We plan to add support for Keras version 1 in the coming updates.

Installation

To install published releases from PyPi (last updated: July 19, 2024) execute:

pip install visualkeras

To update visualkeras to the latest version, add the --upgrade flag to the above commands.

If you want the latest (potentially unstable) features you can also directly install from the github master branch:

pip install git+https://github.com/paulgavrikov/visualkeras

Usage

Generating neural network architectures is easy:

import visualkeras

model = ...

visualkeras.layered_view(model).show() # display using your system viewer
visualkeras.layered_view(model, to_file='output.png') # write to disk
visualkeras.layered_view(model, to_file='output.png').show() # write and show

To help understand some of the most important parameters we are going to use a VGG16 CNN architecture (see example.py).

Default

visualkeras.layered_view(model)

Default view of a VGG16 CNN

Legend

You can set the legend parameter to describe the relationship between color and layer types. It is also possible to pass a custom PIL.ImageFont to use (or just leave it out and visualkeras will use the default PIL font). Please note that you may need to provide the full path of the desired font depending on your OS.

from PIL import ImageFont

font = ImageFont.truetype("arial.ttf", 32)  # using comic sans is strictly prohibited!
visualkeras.layered_view(model, legend=True, font=font)  # font is optional!

Layered view of a VGG16 CNN with legend

Flat Style

visualkeras.layered_view(model, draw_volume=False)

Flat view of a VGG16 CNN

Spacing and logic grouping

The global distance between two layers can be controlled with spacing. To generate logical groups a special dummy keras layer visualkeras.SpacingDummyLayer() can be added.


model = ...
...
model.add(visualkeras.SpacingDummyLayer(spacing=100))
...

visualkeras.layered_view(model, spacing=0)

Spaced and grouped view of a VGG16 CNN

Custom color map

It is possible to provide a custom color map for fill and outline per layer type.

from tensorflow.python.keras.layers import Dense, Conv2D, Flatten, Dropout, MaxPooling2D, ZeroPadding2D
from collections import defaultdict

color_map = defaultdict(dict)
color_map[Conv2D]['fill'] = 'orange'
color_map[ZeroPadding2D]['fill'] = 'gray'
color_map[Dropout]['fill'] = 'pink'
color_map[MaxPooling2D]['fill'] = 'red'
color_map[Dense]['fill'] = 'green'
color_map[Flatten]['fill'] = 'teal'

visualkeras.layered_view(model, color_map=color_map)

Custom colored view of a VGG16 CNN

Hiding layers

Some models may consist of too many layers to visualize or to comprehend the model. In this case it can be helpful to hide (ignore) certain layers of the keras model without modifying it. Visualkeras allows ignoring layers by their type (type_ignore) or index in the keras layer sequence (index_ignore).

visualkeras.layered_view(model, type_ignore=[ZeroPadding2D, Dropout, Flatten])

Simplified view of a VGG16 CNN

Scaling dimensions

Visualkeras computes the size of each layer by the output shape. Values are transformed into pixels. Then, scaling is applied. By default visualkeras will enlarge the x and y dimension and reduce the size of the z dimensions as this has deemed visually most appealing. However, it is possible to control scaling using scale_xy and scale_z. Additionally, to prevent to small or large options minimum and maximum values can be set (min_xy, min_z, max_xy, max_z).

visualkeras.layered_view(model, scale_xy=1, scale_z=1, max_z=1000)

True scale view of a VGG16 CNN Note: Scaled models may hide the true complexity of a layer, but are visually more appealing.

Drawing information text

With the text_callable argument a function can be passed to the layered_view function which can be used to draw text below or above a specific layer. The function should have to following properties:

Accepts two arguments: First the index of the layer in the model. This index ignores layers listed in type_ignore, index_ignore and also ignores layers of class SpacingDummyLayer. The second arguments is the layer object used in the model at the index given in the first argument
Returns two arguments: The first return value is a string containing the text to be drawn. The second return value is a bool value indicating if the text is to be drawn above the box representing the layer.

The following function aims to describe the names of layers and their dimensionality. It would produce the output shown in the figure below:

def text_callable(layer_index, layer):
    # Every other piece of text is drawn above the layer, the first one below
    above = bool(layer_index%2)

    # Get the output shape of the layer
    output_shape = [x for x in list(layer.output_shape) if x is not None]

    # If the output shape is a list of tuples, we only take the first one
    if isinstance(output_shape[0], tuple):
        output_shape = list(output_shape[0])
        output_shape = [x for x in output_shape if x is not None]

    # Variable to store text which will be drawn    
    output_shape_txt = ""

    # Create a string representation of the output shape
    for ii in range(len(output_shape)):
        output_shape_txt += str(output_shape[ii])
        if ii < len(output_shape) - 2: # Add an x between dimensions, e.g. 3x3
            output_shape_txt += "x"
        if ii == len(output_shape) - 2: # Add a newline between the last two dimensions, e.g. 3x3 \n 64
            output_shape_txt += "\n"

    # Add the name of the layer to the text, as a new line
    output_shape_txt += f"\n{layer.name}"

    # Return the text value and if it should be drawn above the layer
    return output_shape_txt, above

Text Callable

Note: Use the padding argument to avoid long text being cut off at the left or right edge of the image. Also use SpacingDummyLayers to avoid interleaving text of different layers.

Reversed view

In certain use cases, it may be useful to reverse the view of the architecture so we look at the back of each layer. For example, when visualizing a decoder-like architecture. In such cases, we can switch draw_reversed to True. The following two figures show the same model with draw_reversed set to False and True, respectively.

visualkeras.layered_view(model, draw_reversed=False) # Default behavior

Default view of a decoder-like model

visualkeras.layered_view(model, draw_reversed=True)

Reversed view of a decoder-like model

Show layer dimensions (in the legend)

It is possible to display layer dimensions in the legend. To do so, set legend=True and show_dimension=True in layered_view. This is a simpler alternative to creating a callable for the text_callable argument to display dimensions above or below each layer.

visualkeras.layered_view(model, legend=True, show_dimension=True)

Show layer dimension in legend mode

FAQ

Feature X documented here does not work

The main branch may be ahead of pypi. Consider upgrading to the latest (perhaps unstable) build as discussed in Installation.

Installing aggdraw fails

This is most likely due to missing gcc / g++ components (e.g. on Elementary OS). Try installing them via your package manager, e.g.:

sudo apt-get install gcc
sudo apt-get install g++

.show() doesn't open a window

You have probably not configured your default image viewer. You can install imagemagick via most package managers:

sudo apt-get install imagemagick

<h2 id="citation-header"> Citation </h2>

If you find this project helpful for your research please consider citing it in your publication as follows.

@misc{Gavrikov2020VisualKeras,
  author = {Gavrikov, Paul},
  title = {visualkeras},
  year = {2020},
  publisher = {GitHub},
  journal = {GitHub repository},
  howpublished = {\url{https://github.com/paulgavrikov/visualkeras}},
}