In [1]: ir = B.in_between(-0.1, 0.3, I) # select current between -0.1 and 0.3
In [2]: l1 = B.linefit(V[ir], I[ir], sig_I[Ir]) # fit the line
In [1]: vh = B.in_between(1.5, 3.5, V) # select voltages between 1.5 and 3.5
In [2]: l2 = B.linefit(V[vh], I[vh], sig_I[vh]) # fit the line
In [1]: vh = (1.5 <= V) & ( V<= 3.5) # select voltages between 1.5 and 3.5
In [2]: l2 = B.linefit(V[vh], I[vh], sig_I[vh]) # fit the line