title: how can I make a loop on time series and plot all them together in R?
body: <p>i've just started using R and some problems with time series analysis occured. Namely, I have data base concerned different products = different product launch id  and I want to plot all of time series (x - weeks_since_launch, y - units_that_sold_that_week) with different colors, presented on one plot. There is also a need before to make a loop and signalize to R to take new time series after 26 weeks_since_launch. Thats how a piece of my data base looks like: <a href="https://imageshack.com/i/euhh3kj" rel="nofollow">https://imageshack.com/i/euhh3kj</a></p>
  
  <p>I am sorry that I cannot even post a code, because I have no idea how to make it.</p>
  
  <p>I would be enormously grateful for any help.</p>