dataset.h File Reference

Training dataset loader. More...

#include "cnn.h"
#include <stddef.h>

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Classes
struct	Sample
	A single labelled training sample. More...
struct	Dataset
	A collection of training samples. More...

Functions
Dataset *	dataset_load (const char *root_dir, int n_threads)
	Load all images from root_dir into a Dataset.
void	dataset_shuffle (Dataset *ds)
	Shuffle the samples in a Dataset in-place (Fisher-Yates).
void	dataset_free (Dataset *ds)
	Free all memory owned by a Dataset.
void	dataset_print_info (const Dataset *ds)
	Print a summary of the dataset to stdout.

Detailed Description

Training dataset loader.

Expects a root directory with one sub-directory per letter:

training_data/ A/ image1.png image2.png … B/ … … Z/ …

Each image is loaded with SDL2, converted to grayscale, and resized to CNN_IMG_H × CNN_IMG_W. The resulting pixel values are normalised to [0, 1].

Parallelism: loading can be parallelised over POSIX threads; the number of worker threads is controlled by the caller.

Function Documentation

dataset_free()

void dataset_free

(

Dataset *

ds

)

Free all memory owned by a Dataset.

Parameters

ds	Dataset returned by dataset_load(). No-op if NULL.

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dataset_load()

Dataset * dataset_load	(	const char *	root_dir,
		int	n_threads )

Load all images from root_dir into a Dataset.

Opens sub-directories named A–Z. For each PNG/JPG image found, loads it with SDL2, converts to grayscale, resizes to 28×28, normalises to [0, 1], and appends a Sample to the dataset. Non-image files are silently skipped.

Parameters

root_dir	Path to the training data root (e.g. "training_data/").
n_threads	Number of POSIX loader threads (1 = single-threaded).

Returns

Pointer to a heap-allocated Dataset, or NULL on error. Free with dataset_free().

Note

Requires SDL2 and SDL2_image to be linked.

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dataset_print_info()

void dataset_print_info

(

const Dataset *

ds

)

Print a summary of the dataset to stdout.

Shows the total number of samples and the per-class distribution.

Parameters

ds	Dataset to describe.

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dataset_shuffle()

void dataset_shuffle

(

Dataset *

ds

)

Shuffle the samples in a Dataset in-place (Fisher-Yates).

Parameters

ds	Dataset to shuffle.

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