I have two time series for example:

s1:

  2017-01-06 18:39:30    100

  2017-01-07 18:39:28    101

and

s2:

2017-01-07 18:00:00     90

2017-01-08 18:00:00    105

I want to plot these in a Chartjs chart, however it seems that Chartjs only takes one x-axis array (or label in Chartjs terminology).

So my question is what is the best way to plot both of these?

My approach was to write a function (in python, although the language doesn't really matter for this part) that iterates through both time series and creates 3 new arrays which is in the format apparently Chartjs needs based off the 1st example here: https://www.sitepoint.com/introduction-chart-js-2-0-six-examples/

The algorithm (in sudo code) goes like:

    # inputs are initial time series s1 and s2

    y1 = [] # to hold new s1 data values

    y2 = [] # to hold new s2 data values

    x  = [] # to hold times



    # iterate through longest series s1 or s2

    if s1[idx].time > s2[idx].time

      x.append(s1[idx].time)

      y1.append(s1[idx].data)

      # y2 appends the linear interpolation of 

      # of closest y2 points



    if (s1[idx].time < s2[idx].time)

      x.append(s2[idx].time)

      # opposite of above. ie. swap y1<->y2, s1->s2



    else # they have the same time

      x.append(s1[idx].time)

      y1.append(s1[idx].data)

      y2.append(s2[idx].data) 

There are a couple other conditional checks for when data runs out of the shorter series but that is the main logic. After which I have 3 arrays that I can now add to chart js via one time/label array/x-axis and two data arrays. However this seems WAY more complicated than it should be considering how common I assume this use case is. Any help or advice is greatly appreciated.