# split-bidirectional-migration model used in δaδi.

# The defined model inserted into a modified Demographics2D.py file:

def split_bidirmig(params, ns, pts):

    """
    params = (nu1,nu2,T,m12,m21)
    ns = (n1,n2)

    Split into two populations of specified size, with bidirectional migration.

    nu1: Size of population 1 after split.
    nu2: Size of population 2 after split.
    T: Time in the past of split (in units of 2*Na generations)
    m12: Migration rate 2>>1
    m21: Migration rate 1>>2
    n1,n2: Sample sizes of resulting Spectrum
    pts: Number of grid points to use in integration.
    """
# modify params to include bidirectional gene flow
    nu1,nu2,T,m12,m21 = params

# use grid
    xx = Numerics.default_grid(pts)

# use the grid and split pops

    phi = PhiManip.phi_1D(xx)
    phi = PhiManip.phi_1D_to_2D(xx, phi)

# allow for gene flow between the pops bidirectional m12,m21

    phi = Integration.two_pops(phi, xx, T, nu1, nu2, m12=m12, m21=m21)

#calculate and return the spectra

    fs = Spectrum.from_phi(phi, ns, (xx,xx))
    return fs

def split_bidirmig_mscore(params):
    """
    ms core command for split_bidirmig.
    """
    nu1,nu2,T,m12,m21 = params

    command = "-n 1 %(nu1)f -n 2 %(nu2)f "\
            "-ma x %(m12)f %(m21)f x "\
            "-ej %(T)f 2 1 -en %(T)f 1 1"

    sub_dict = {'nu1':nu1, 'nu2':nu2, 'm12':m12, 'm21':m21, 'T': T/2}
    
    return command % sub_dict