Optimize 102Flowers dataset reading speed

[GT-ZhangAcer]

PR types

Others

PR changes

Others

Describe

Fix slow data reading, In the old version, one epoch read time of this data set was about 5371 seconds(MacBook Pro Retina, 13-inch, Early 2015 2.7 GHz), and a batch(32) took 211 seconds, It's too painful to use.
Now decompress the data in advance (about 10 seconds). Each epoch of reading takes about 3 seconds(MacBook Pro Retina, 13-inch, Early 2015 2.7 GHz), and a batch(32) takes 0.017 seconds.

Test sample

import paddle
import time

start = time.time()
data = paddle.vision.datasets.Flowers()


for idx, _ in enumerate(data):
    print(idx)

print("cost:", time.time() - start)

[paddle-bot-old]

Thanks for your contribution!
Please wait for the result of CI firstly. See Paddle CI Manual for details.

[liuhuiCNN]

LGTM

[paddle-bot-old]

Sorry to inform you that 33ab88b's CIs have passed for more than 7 days. To prevent PR conflicts, you need to re-run all CIs manually.

[TCChenlong]

LGTM