how to write n X p value of o_var or d_var

[seamman]

i always have problem of using gravity model when i want to calculate n x p value of o_var or d_var
code like:
o_cap = np.array(df[['Oi_1','Oi_2']])
d_cap = np.array(df[['Dj_1','Dj_2']])
or
o_cap = np.array(df[['Oi_1','Oi_2']]).T
d_cap = np.array(df[['Dj_1','Dj_2']]).T
model = Gravity(flows,o_cap,d_cap,cost,'exp')

and then ,the model break down! i have tried many other ways, but it seems that none of those samples work. is there a sample way to adjust the code?