## neural-classifier

2022-07-08

Classification of samples based on neural network.

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# Neural-classifier

`neural-classifier`

is a neural network library based on the first chapters
from this book. It is divided on
two systems: `neural-classifier`

which is a general API for neural networks
and `neural-classifier/mnist`

which contains helper functions for working with
MNIST/EMNIST datasets. For API documentation visit
this page.

## How to work with MNIST dataset?

- Unpack files in
`mnist/dataset`

directory. - Load
`neural-classifier/mnist`

system:`(ql:quickload :neural-classifier/mnist)`

. - Eval
`(neural-classifier-mnist:load-mnist-database)`

(this will take about 10-15 seconds). - Create a neural network:
`(defparameter *nn* neural-classifier-mnist:make-mnist-classifier 35)`

where`35`

is a number of hidden neurons. - Execute
`(neural-classifier-mnist:train-epochs *nn* 10)`

to train the network for 10 epochs. This function will return data about the network's accuracy for each epoch. - To test your own digits convert them to
`784x1`

matrix of type`magicl:matrix/single-float`

and pass it to`neural-classifier:calculate`

function. - Also you can play with some other hyper-parameters, not only the number of
hidden neurons.
`neural-classifier:*learn-rate*`

is how fast gradient descent algorithm works (i.e. how fast your network learns),`neural-classifier:*decay-rate*`

is related to regularization and should be about`5/N`

where`N`

is a number of training samples. Zero means no regularization.

## How to build custom nets and data?

See GH pages for this project (link above). In general you need to write
functions which translate your data and labels into `magicl:matrix/single-float`

matrices. Then you create a net with `neural-classifier:make-neural-network`

function and `snakes`

generator which returns conses in the form `(DATA . LABEL)`

. To train a network for one epoch you call
`(neural-classifier:train-epoch)`

.

## Dependencies

`blas`

and`lapack`

foreign libraries.`magicl`

for matrix operations.`nibbles`

for loading MNIST data.

`magicl`

and `nibbles`

can be downloaded with `quicklisp`

.

## What if the network shows good accuracy but fails to recognize my own digits?

If the accuracy returned by `train-epochs`

is good, but the network fails to
recognize digits draws by your own hand, try EMNIST database instead of
MNIST. Copy four `emnist-digits-*`

files to your MNIST directory **preserving
the name of destination files**. Images in EMNIST set are transposed (x and y
coordinates swapped), so do the same with your own images.