Step-by-step guide

To do that, you will have to change the dimension of the super page ( the output) and of the page.

Let's say that you want an A4 in portrait mode. You will have to set  super_page_x_length and the page_x_length to 21., and super_page_y_length and the page_y_length to 29.7.

Python Example Portrait Mode 
from Magics.macro import *

#Setting output
output = output(
    output_formats                = ['png'],
    output_name                   = 'portrait',
    output_name_first_page_number = 'off',
    super_page_x_length =  21.,
    super_page_y_length =  29.7,
    page_x_length =  21.,
    page_y_length =  29.7,
    )
area = mmap(subpage_lower_left_longitude = -30.,
        subpage_lower_left_latitude = -10.,
        subpage_upper_right_longitude = 50.,
        subpage_upper_right_latitude = 80.,
        )
#Setting the coastlines
background = mcoast(
    map_coastline_land_shade        = 'on',
    map_coastline_land_shade_colour = 'cream')

#Adding a title
title = mtext(text_lines = ["Plot in portrait mode"],
            text_font_size = 1. ,
            )

#Plotting
plot(output, area, background, title)