Is there a proper way to track how often an item was sold/bought in a given time?

I'm trying to code an api wrapper for flipping.To do that I need to find a way to find out how often an item was bought and sold in a 24h timespan.Is there a proper way to get this information dirtectly or do I have to run a server the whole time tracking ALL the items and calculate the differences?

No, that information is not exposed by the api. Only current number of orders but nothing about what happens in between updates.Most TP websites use the changes in number of orders to calculate volume, which for low volume items should be fairly accurate. For high volume items this is missing way too much.

@Soulkeeper.3972 said:I'm trying to code an api wrapper for flipping.To do that I need to find a way to find out how often an item was bought and sold in a 24h timespan.Is there a proper way to get this information dirtectly or do I have to run a server the whole time tracking ALL the items and calculate the differences?

As noted above, the API exposes buy offers and sales listings; it does not expose what causes those to change over time. Sites like GW2 BLTC estimate sales by presuming that all changes to the supply are due to insta-sells. They estimate purchases by presuming that all changes to demand are due to insta-buys.

Obviously, those assumptions aren't accurate. For flipping, however, they get you in the right ballpark.

Most analytics I've seen use a fudge factor to account for the differences by some sort of formula using price volatility and velocity. That might or might not be useful.

What's more important is that in equilibrium markets, the errors due to using such estimates are comparable across all items with similar volatility/velocity and incomparable otherwise. For example, you can compare Sunrise & Twilight easily and you can compare Vials of Powerful Blood with Elaborate Totems; you can't compare high-priced/low volume shinies and low-prices/high-volume commodities.

Take a look at GW2 BLTC and Silveress Golden's websites; the latter has especially helpful documentation.

Ok, then I will need to keep track of the updates. Thanks for the answere. Its ok that its not pin point accurate I just need to get an overview if the item is "dead" or not. Sometimes you have items with high supply and demand but noone is trading them.

@Soulkeeper.3972 said:Sometimes you have items with high supply and demand but noone is trading them.

Tracking delta supply|demand from API is good enough for that, yes.