[FIX] change data load function.

[col14m]

Changed data load function. Dataset parsing has been accelerated from about 5 hours to 10 minutes.

Motivation

Very slow dataset parsing. The proposed changes speed up parsing from about 5 hours to 10 minutes.

Modification

Only two lines.

[CLAassistant]

All committers have signed the CLA.

[col14m]

Don't quite understand lint problem.

[Xiangxu-0103]

Please fix lint following this guidance.

[col14m]

I had run pre-commit and got something strange (see the screen). Is it normal?

[JingweiZhang12]

@col14m Thanks for your code for speeding up parsing. Cool! The lint problem is our negligence about another PR check. I have updated this PR.

[OpenMMLab-Assistant-004]

Hi @col14m,

We'd like to express our appreciation for your valuable contributions to the mmdetection3d. Your efforts have significantly aided in enhancing the project's quality.
It is our pleasure to invite you to join our community thorugh Discord_Special Interest Group (SIG) channel. This is a great place to share your experiences, discuss ideas, and connect with other like-minded people. To become a part of the SIG channel, send a message to the moderator, OpenMMLab, briefly introduce yourself and mention your open-source contributions in the #introductions channel. Our team will gladly facilitate your entry. We eagerly await your presence. Please follow this link to join us: ​https://discord.gg/UjgXkPWNqA.

If you're on WeChat, we'd also love for you to join our community there. Just add our assistant using the WeChat ID: openmmlabwx. When sending the friend request, remember to include the remark "mmsig + Github ID".

Thanks again for your awesome contribution, and we're excited to have you as part of our community!