wikipedia数据集预处理

发布于2020-02-26 11:50 阅读(1739) 评论(0) 点赞(13) 收藏(3)

Notes

wikipedia^[1] 用于检索的数据集，包含 2866 个样本、10 个类，图像、文本两个模态。
想按照 [2] 的设置处理数据，而 [2] 的设置应该来自 [3]，即 images 用 CaffeNet^[4] 提取 fc7 层^[5] 的 4096 维特征，texts 用 word2vec^[6] 提取每个单词的 100 维词向量并取平均。
暂时用 Keras 预训练的 VGG16^[7,8] 代替 CaffeNet，参考 [12]；word2vec 特征用 gensim^[9] 库生成，参考 [13, 14]。

Data

从 [10] 下载，解压之后有 trainset_txt_img_cat.list 和 testset_txt_img_cat.list 两个文件，里面每行代表一个样本，分 3 列：text 文件名、image 文件名、class id。
text 数据在 texts/ 下，装在 .xml 文件里。本想用 minidom^[11] 解析，但因为一些特殊符号（比如单独的 &）解析不了，未找到好方法，暂时手动解析。
image 数据在 images/ 下，分类放在不同文件夹。

Code

import os
from os.path import join
import numpy as np

from gensim.models import Word2Vec

from tensorflow.keras.applications.vgg16 import VGG16
from tensorflow.keras.preprocessing import image
from tensorflow.keras.applications.vgg16 import preprocess_input
from tensorflow.keras.models import Model


P = "wikipedia_dataset"
IMG_P = "images"
TXT_P = "texts"
TRAIN_LIST = "trainset_txt_img_cat.list"
TEST_LIST = "testset_txt_img_cat.list"

os.chdir(P)  # 切去解压目录
print(os.getcwd())
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20

sample list

将 sample list 读出来，方便以同一顺序处理 images、texts、labels

ls_img = []
ls_txt = []
ls_lab = []

for fname in (TRAIN_LIST, TEST_LIST):
    with open(fname, "r") as f:
        for line in f:
            txt_f, img_f, lab = line.split()
            #txt_f = join(TXT_P, txt_f, ".xml")
            #img_f = join(IMG_P, img_f, ".jpg")
            ls_img.append(img_f)
            ls_txt.append(txt_f)
            ls_lab.append(int(lab))

print(len(ls_img), len(ls_txt), len(ls_lab))
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15

labels

labels 读出来就可以直接保存

labels = np.asarray(ls_lab)
print(labels.shape)
np.save("labels.npy", labels)
1
2
3

texts

手动解析 .xml，清除一些多余的符号

def parse(fn):
	"""手动解析 xml：读 <text> </text> 之间的部分"""
    res = ""
    flag = False
    with open(fn, "r", encoding="utf-8") as f:
        for line in f:
            line = line.strip()
            if not line:
                continue
            if line == "</text>":
                break
            if flag:
                res += " " + line
            if line == "<text>":
                flag = True
    return res


def clean(strings, pattern):
	"""驱邪……"""
    return [s.replace(pattern, "") for s in strings]


"""解析 xml"""
sentences = []
for txt_f in ls_txt:
    txt_f = join(TXT_P, "{}.xml".format(txt_f))
    # print(txt_f)
    doc = parse(txt_f)  # 手动解析
    # doc = minidom.parse(txt_f).documentElement.getElementsByTagName("text")[0].childNodes[0].data
    words = doc.split()
    # 清除多余符号
    for pat in (",", ".", "!", "?", "''", "(", ")", "\"", ":", ";", "{", "}", "[", "]"):
        words = clean(words, pat)
    sentences.append(words)

print(len(sentences))


"""训练 word2vec 模型"""
# [3] 说用 skip-gram
w2v = Word2Vec(sentences, size=100, min_count=5, iter=50, sg=1)  # sg = skip-gram


"""提取文本特征"""
texts = np.zeros([len(sentences), 100])
for i, s in enumerate(sentences):
    cnt = 0
    for w in s:
        if w in w2v:
            cnt += 1
            texts[i] += w2v[w]
    # 取平均词向量
    texts[i] /= cnt

# 保存
np.save("texts.w2v.100.npy", texts)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57

images

将图片全部复制到同一个目录，方便操作。用 VGG16 提特征

ALL_IMG_P = "images_all"
if not os.path.exists(ALL_IMG_P):
    os.makedirs(ALL_IMG_P)


"""全复制到 ALL_IMG_P"""
for cls in os.listdir(IMG_P):
    cls_d = join(IMG_P, cls)
    # print(os.listdir(cls_d))
    for img in os.listdir(cls_d):
        # os.system("cp {} {}".format(join(cls_d, img), ALL_IMG_P))  # linux
        os.system("copy {} {}".format(join(cls_d, img), ALL_IMG_P))  # windows
print(len(os.listdir(ALL_IMG_P)))


"""提特征"""
base_model = VGG16(weights='imagenet')
# print(base_model.summary())
model = Model(inputs=base_model.input, outputs=base_model.get_layer('fc2').output)
# print(model.summary())

images = []
for i_name in ls_img:
    img_f = join(ALL_IMG_P, "{}.jpg".format(i_name))
    img = image.load_img(img_f, target_size=(224, 224))
    x = image.img_to_array(img)
    x = np.expand_dims(x, axis=0)
    x = preprocess_input(x)
    images.append(model.predict(x))

images = np.vstack(images)
print(images.shape)

# 保存
np.save("images.vgg16.npy", images)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35