jsanim | Javascript Animation Library | Animation library

I've reformatted your code, but I think your main issue was that your dataframes start with a index of 1, but when you're calling your animation with frames=4, it's calling update() with i=[0,1,2,3]. Therefore when you do get_data_x(0) you raise a KeyError: 'the label [0] is not in the [index]'

As per the documentation, frames= can be passed an iterable instead of an int. Here, I simply pass the index of your dataframe, and the function will iterate and call update() with each value. Actually, I decided to pass the intersection of your two dataframe indexes, that way, if there is one index present in one dataframe but not the other, it will not raise an Error. If you are garanteed that your two indexes are the same, then you could just do frames=df_x.index