Creating a time series that displays the minimum price for multiple offers of the same item that run for discrete time periods

[Beau Jackson]

Hello

I am currently working on a project which observes an identical product that being offered by multiple sellers for discrete periods of time. I am interested in understanding how the cheapest price of the product has changed with time. To give a bit more understanding, I have included a table below which illustrates what our dataset looks like:

Seller ID	Startdate	Enddate	Price
A	1jun2017	2jan2018	100
A	1jan2018	20may2018	110
B	5apr2017	18jul2018	130

...

Basically the desired output for this project would include the cheapest price provided by each seller for every date between 1 Jan 2016 and 31 May 2019. I have tried to show what this might look like below:

Date	A	B
2jan2018	100	130
3jan2018	110	130

...

The closest I have managed to get to this output is through a loop - however, my knowledge of looping is somewhat limited and I haven't been able to get the data into my desired format. The code I used is as follows:

forvalues i = 20454(1)21700 {
table seller if startdate<`i' & enddate>`i', c(min price)
}

As you can probably see, the output here is multiple tables and is not particularly usable for my research.

I would really appreciate any help that anyone can provide me!

Thanks

[Beau Jackson]

I managed to work this one out. For anyone who is experiencing similar problems:

gen enddate2 = enddate - 20453
gen startdate2 = startdate - 20453

encode sellerid, gen(ensellerid)

set matsize 11000

matrix t1 = J(1247,5,.)
forvalues i = 1(1)1247 {
forvalues j = 1(1)2 {
summarize price if enddate2>=`i' & startdate2<=`i' & ensellerid==`j'
matrix t1[`i',`j'] = r(min)
}
}