[Solved]-How to use sparse arrays with C3 charts?-d3.js

You can use empty array as entry value. This works ok:

[["data1",30,200,100,400,150,250],[],[],["data2",50,20,10,40,15,25]]

And modify your filtering function to skip arrays without length:

function checkIfNull(x) {
    return (x.length);
}

See updated fiddle