Gelbooru

Notice: Visit your account options to access your Patreon rewards for March. Come join our Discord! Last chance for being able to disable ads via Patreon!

Ticket Information - ID: #835


ID:Category:SeverityReproducibilityDate SubmittedUpdated By:
0000835Feature RequestnormalN/A04/28/16 12:43PMAlzarath
ReporterAlzarath
Assigned to:geltas
Resolution:Open
View StatusPublic
Version:
Target Version:N/A
Summary:Random image from tags for API
Description:It would be nice if we could fetch a random image from given tags.
Additional Info:
Alzarath replied at 2016-04-29 07:39:20
For example, adding &random=1 would fetch random images from all of the available images that could be found from the site that contains the &tags results.

It would be preferred that they're sorted randomly so results with few images don't end up giving the same order of results.

Jerl replied at 2016-04-29 18:53:36
For now, it's pretty simple to just select a random image yourself programmatically.

Take
"<posts count="x" offset="0">"

Take x and integer divide it by 100 to get n. Since it's integer division, it'll ignore the remainder.

Generate a random number r between 0 and n. That'll give you a random page.

Load the search again with the offset set to r * 100. That'll load the random page.

Load the post entries into an array or list. Generate a random number from 0 through the number of posts on the page - 1 (should normally be 99 unless you managed to get the last page). Select the entry at that index from the array/list. You have your random post.

For my purposes, I actually just use that last paragraph and only select a random post from the first page of results since that's sufficient for my needs, but your needs might be different.

Alzarath replied at 2016-05-02 00:45:20
No doubt it'd be pretty easy to get it on the client-side, but needing to fetch 100 results for the sake of adequate randomization just seems unnecessarily bandwidth-intensive. As someone without a high-end internet connection available to them, it can be a bit of a big deal.

I'll probably do it for now, but I'd like if it were supported by the API in the end.

Jerl replied at 2016-05-02 02:04:13
You don't need to fetch 100 results at a time - you can change the number of results the API gives you per page to whatever you want. 100 is only the default.

If you're short on bandwidth, you can instead do it like this:

First, load the API for the search you're trying to perform INCLUDING the limit of 1 post per page. You can do this by adding "&limit=1" to the end of the request URL. You'll get a result something like

"<posts count="100651" offset="0">"

Generate a random number smaller than the count. In this case, I'm going to use 23515. Set that number as the offset. You can do that by adding "&pid=23515" to the end of the previous request URL. You'll get something like

"<posts count="100651" offset="23515">
<post height="1131" score="50" file_url="http://simg4.gelbooru.com/images/05/47/05472a6c5c0c4b3aad40d99467e86318.jpeg" parent_id="" sample_url="http://simg4.gelbooru.com/images/05/47/05472a6c5c0c4b3aad40d99467e86318.jpeg" sample_width="800" sample_height="1131" preview_url="http://gelbooru.com/thumbnails/05/47/thumbnail_05472a6c5c0c4b3aad40d99467e86318.jpg" rating="e" tags=" 5boys 5girls aihara_enju black_bullet black_hair blonde_hair blue_eyes blue_hair braid everyone fellatio ikuma_shougen loli multiple_boys multiple_girls oral orange_hair pink_hair satomi_rentarou senju_kayo short_hair twintails y.ssanoha " id="2317366" width="800" change="1432247980" md5="05472a6c5c0c4b3aad40d99467e86318" creator_id="124225" has_children="false" created_at="Thu Jul 03 11:35:04 -0500 2014" status="active" source="http://www.pixiv.net/member_illust.php?mode=medium&illust_id=44393104" has_notes="false" has_comments="true" preview_width="106" preview_height="150"/>
</posts>"

That's your random post. Total bandwidth used is ~1.5-2KB, which is a negligible difference from just loading one page.

Ultimately this is probably the better way to do it than the method I explained above, but requires more understanding of how the API works.

Alzarath replied at 2016-05-02 06:52:25
Oh, I understand what you mean now. Yeah, that could definitely work for what I need, only I've been using the json mode which doesn't not seem to have a `posts count`.

I'll look into seeing if I can get xml to work with my application. It would be nice if the json included this information as well, though.