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""" A dataset reader that extracts images from folders
Folders are scanned recursively to find image files. Labels are based
on the folder hierarchy, just leaf folders by default.
Hacked together by / Copyright 2020 Ross Wightman
"""
import os
from typing import Dict, List, Optional, Set, Tuple, Union
from timm.utils.misc import natural_key
from .class_map import load_class_map
from .img_extensions import get_img_extensions
from .reader import Reader
def find_images_and_targets(
folder: str,
types: Optional[Union[List, Tuple, Set]] = None,
class_to_idx: Optional[Dict] = None,
leaf_name_only: bool = True,
sort: bool = True
):
""" Walk folder recursively to discover images and map them to classes by folder names.
Args:
folder: root of folder to recrusively search
types: types (file extensions) to search for in path
class_to_idx: specify mapping for class (folder name) to class index if set
leaf_name_only: use only leaf-name of folder walk for class names
sort: re-sort found images by name (for consistent ordering)
Returns:
A list of image and target tuples, class_to_idx mapping
"""
types = get_img_extensions(as_set=True) if not types else set(types)
labels = []
filenames = []
for root, subdirs, files in os.walk(folder, topdown=False, followlinks=True):
rel_path = os.path.relpath(root, folder) if (root != folder) else ''
label = os.path.basename(rel_path) if leaf_name_only else rel_path.replace(os.path.sep, '_')
for f in files:
base, ext = os.path.splitext(f)
if ext.lower() in types:
filenames.append(os.path.join(root, f))
labels.append(label)
if class_to_idx is None:
# building class index
unique_labels = set(labels)
sorted_labels = list(sorted(unique_labels, key=natural_key))
class_to_idx = {c: idx for idx, c in enumerate(sorted_labels)}
images_and_targets = [(f, class_to_idx[l]) for f, l in zip(filenames, labels) if l in class_to_idx]
if sort:
images_and_targets = sorted(images_and_targets, key=lambda k: natural_key(k[0]))
return images_and_targets, class_to_idx
class ReaderImageFolder(Reader):
def __init__(
self,
root,
class_map='',
input_key=None,
):
super().__init__()
self.root = root
class_to_idx = None
if class_map:
class_to_idx = load_class_map(class_map, root)
find_types = None
if input_key:
find_types = input_key.split(';')
self.samples, self.class_to_idx = find_images_and_targets(
root,
class_to_idx=class_to_idx,
types=find_types,
)
if len(self.samples) == 0:
raise RuntimeError(
f'Found 0 images in subfolders of {root}. '
f'Supported image extensions are {", ".join(get_img_extensions())}')
def __getitem__(self, index):
path, target = self.samples[index]
return open(path, 'rb'), target
def __len__(self):
return len(self.samples)
def _filename(self, index, basename=False, absolute=False):
filename = self.samples[index][0]
if basename:
filename = os.path.basename(filename)
elif not absolute:
filename = os.path.relpath(filename, self.root)
return filename
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