About JSON data structure

[Jorge Braccini]

Hello, there! Just found this group.

I was in the enterprise of developing market insight through statistics, and found your API very cool. Firstly, I tried to do it through ImportXML and using a custom script to Import JsON to spreadsheets (Google Spreadsheets), but found that ImportXML is not wokring very well on that platform and as I am a PC user who switchs from Win to Linux, it didn't make sense to do that on Excel, for instance.

So I decided to go on developing a web version and tried to interact directly with this endpoint:

http://api.eve-central.com/api/marketstat/json

I queried to get some dummy data about a couple items and specified a system as well, like this:

http://api.eve-central.com/api/marketstat/json?typeid=10842,32780,4403,2301,19739,31796,28606,2048,32880,17456,22761,22544,22291&usesystem=30000142

I am currently getting a response such as the following, would you please specify those properties? I have an idea of the market, but some properties as 'generated' and 'stdDev' are confusing, and didn't found any documentation on this. If you have a link, please care to share.

Thanks in advance!

1. [0:{,…}
1. all:{forQuery: {bid: null, types: [10842], regions: [], systems: [30000142], hours: 24, minq: 1},…}
2. buy:{forQuery: {bid: true, types: [10842], regions: [], systems: [30000142], hours: 24, minq: 1},…}
3. sell:{forQuery: {bid: false, types: [10842], regions: [], systems: [30000142], hours: 24, minq: 1},…}
1. avg:3041823.3641025648
2. fivePercent:2676986.249275363
3. forQuery:{bid: false, types: [10842], regions: [], systems: [30000142], hours: 24, minq: 1}
1. bid:false
2. hours:24
3. minq:1
4. regions:[]
5. systems:[30000142]
6. types:[10842]
4. generated:1471385164685
5. highToLow:false
6. max:4000000.02
7. median:3679999
8. min:2676985.92
9. stdDev:397872.90683150874
10. variance:158302849990.5544
11. volume:1314
12. wavg:3438731.4808295276
13. 
    

[Miasma]

Hello o/

I'm just another peon, and am not involved with the development of this api in any means, so take my assumptions with a grain of salt.

From my experience and reading stdDev typically means Standard Deviation, which is a mathematically derived "limit" to the expected market price above or below the average price.  Looking at the value for stdDev you could reasonably expect the market prices to be anywhere between 397,872.91 above or below the average e.g. within the range of 3040858.57 to 3,836,604.39.  Be careful of this calculation when dealing with low volumes though, as they are susceptible to market manipulation by flooding the market with orders for prices much higher or lower than the average (for example someone places a huge buy order for the item at 1isk per unit for something that normally costs 1,000,000,000isk).

As for the generated field, I would expect that to be the date:time that the data was scrounged together and sent to you by the server.  I don't know what format they're using... maybe the number of seconds since the epoch...  Need another person's expert opinion on that one.

[Yann Ramin]

Correct on both fronts. Generated is the number of seconds since unix epoch (UTC). 

https://github.com/theatrus/eve-central.com/blob/master/core/src/main/scala/com/evecentral/OrderStatistics.scala#L164

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