I think a legend would be helpful (line vs bars, solid bars vs empty bars. I'm assuming that has to do with the fact that you're collating several averages). Is the 15 minute limit just because the chart just got put up? I think it'd be nice to see a longer term chart (you can get a long term chart from dvc to btc at vircurex, but not straight to USD).
Thanks for putting it together!
Thanks for the feedback. I agree it needs a legend, and I'll get that in.
I'm not 100% sure how well you know candlestick charts, so I'm assuming you know less based on your question but forgive me if you already know this stuff. With the solid bars vs empty bars, those are normal for a candlestick chart, although google charts has it backwards to other charting software for some reason, something I'll also look into - usually a lighter or green bar represents a rise in price from opening time to close in the charting period (15min is the total time period per candle in this chart's case), and darker or red for down. The bars are supposed to represent the difference in open and closing price in the chart period (the solid bar bit) and the lines coming out of the bars are the high and low during the 15 minute period, where the price reached but didn't remain.
The 15 minute limit was what was asked for in the spec - that's not 15 minutes of data, but 15 minutes of data per candlestick. Other periods are useful definitely useful too, and once I've got my data sorted out I'll add some different periods. I don't think there's much value in putting shorter times for dvc/usd atm, but the daily and weekly charts (where each candlestick represents price movement for a whole day or week respectively), would be very useful over time to see the long term value of a devcoin.
Regarding collating averages, that just means I'm using an average market spot price, as different exchanges have different prices - eg mtgox is currenty $680/coin whereas 3 others are $630/coin. I use 4 markets for the btc/usd price, and 2 for the dvc/btc price.
The problem with history was getting it through an API. While vircurex has the data themselves, they may not necessarily release it for others to see. Pretty much everyone offers a public ticker so we can get the last trade price easily, just not all the trades from the beginning of time etc. I might try trawling one of the chart pages, but that's generally easier said than done.