How to place multiple graphs in same coordinate system (pandas,mathplotlib) -> look pic in short how to set graphs in same coordinate system, not separated as in pic each in its own coordinate system in one frame....
Problem is with the dtype of your y values. It's &quot;object&quot; and thus matplotlib thinks two object containing same float value are different.
Use,
y  = a.astype(float).values
y1 = b.astype(float).values
y2 = c.astype(float).values