A script that combines margins when pasting a number of graphs on tiles with gnuplot

As the title says, instead of a φ (..) memo.

def margin( n, nhor, nver ) :
    '''
    return top, bottom, left and right margins for the gnuplot command to describe diagrams as tile like arrangement.\n
    inputs: n is the number of diagrams and nhor is the number of column.
    '''
    def margin_fmt( t, b, l, r ) :
        return [ "set tmargin %d" % t, # top
                 "set bmargin %d" % b, # bottom
                 "set lmargin %d" % l, # left
                 "set rmargin %d" % r ]# right
    ret = []
    for i in range(n) :
        t,b,l,r = 0,0,0,0
        # vertical orientation
        if   i / nhor == 0 :
            t = 2
        elif i / nhor == nver - 1 :
            b = 2
            # horizontal orientation
        if   i % nhor == 0 :
            l = 2
        elif i % nhor == nhor - 1 :
            r = 2

        ret.append( margin_fmt( t, b, l, r ) )

    return ret


if __name__ == "__main__" :
    n = 2*6
    nhor = 5
    def get_the_number_of_rows( n, nhor ) :
        if   n % nhor == 0 : nver = n / nhor
        elif n % nhor != 0 : nver = n / nhor + 1
        return nver
    nver = get_the_number_of_rows(n,nhor)

    for _ in margin(n,nhor,nver) :
        print _

The execution result is as follows.

['set tmargin 2', 'set bmargin 0', 'set lmargin 2', 'set tmargin 0']
['set tmargin 2', 'set bmargin 0', 'set lmargin 0', 'set tmargin 0']
['set tmargin 2', 'set bmargin 0', 'set lmargin 0', 'set tmargin 0']
['set tmargin 2', 'set bmargin 0', 'set lmargin 0', 'set tmargin 0']
['set tmargin 2', 'set bmargin 0', 'set lmargin 0', 'set tmargin 2']
['set tmargin 0', 'set bmargin 0', 'set lmargin 2', 'set tmargin 0']
['set tmargin 0', 'set bmargin 0', 'set lmargin 0', 'set tmargin 0']
['set tmargin 0', 'set bmargin 0', 'set lmargin 0', 'set tmargin 0']
['set tmargin 0', 'set bmargin 0', 'set lmargin 0', 'set tmargin 0']
['set tmargin 0', 'set bmargin 0', 'set lmargin 0', 'set tmargin 2']
['set tmargin 0', 'set bmargin 2', 'set lmargin 2', 'set tmargin 0']
['set tmargin 0', 'set bmargin 2', 'set lmargin 0', 'set tmargin 0']