Description
Metview Macro Library function. Used to plot a straight line onto a non-cylindrical map projection. Internally, the line is split into a number of segments and the returned result is an Input Visualiser object which can be passed to the plot() command along with an optional Graph Plotting object.
Usage
definition mvl_geoline(lat1 : number, lon1 : number, lat2 : number, lon2 : number, incrm : number)
The first four parameters define the end-points of the line. Parameter incrm specifies the increment, in degrees, into which the line should be split.
Example
Download source and data
Geoline on Map Example
# Metview Macro
# **************************** LICENSE START ***********************************
#
# Copyright 2018 ECMWF. This software is distributed under the terms
# of the Apache License version 2.0. In applying this license, ECMWF does not
# waive the privileges and immunities granted to it by virtue of its status as
# an Intergovernmental Organization or submit itself to any jurisdiction.
#
# ***************************** LICENSE END ************************************
# ---------------------------------------------------------------
# Description: Demonstrates how to plot a line on any map
# projection using the Macro Library function
# mvl_geoline.
# ---------------------------------------------------------------
# set up the shaded coastlines
land_sea_shade = mcoast(
map_coastline_land_shade : "on",
map_coastline_land_shade_colour : "RGB(0.98,0.95,0.82)",
map_coastline_sea_shade : "on",
map_coastline_sea_shade_colour : "RGB(0.85,0.93,1)"
)
# define the geographic view
view = geoview(
map_projection : "polar_stereographic",
map_area_definition : "corners",
area : [-5,-30,10,84], # S,W,N,E
coastlines : land_sea_shade
)
# create a geoline broken into 1-degree segments
line_increment_in_degrees = 1
# coordinates of line end-points given as lat1,lon1,lat2,lon2
geoline = mvl_geoline(55, -22, 5, 45, line_increment_in_degrees)
# define the plotting attributes for the line
line_visdef = mgraph(
graph_line_colour : "red",
graph_line_thickness : "4",
graph_line_style : 'dash'
)
# define the output plot file
setoutput(pdf_output(output_name : 'geoline_on_map'))
# plot the line on the map
plot(view, geoline, line_visdef)
Geoline on Map Example
# Metview Example
# **************************** LICENSE START ***********************************
#
# Copyright 2018 ECMWF. This software is distributed under the terms
# of the Apache License version 2.0. In applying this license, ECMWF does not
# waive the privileges and immunities granted to it by virtue of its status as
# an Intergovernmental Organization or submit itself to any jurisdiction.
#
# ***************************** LICENSE END ************************************
# ---------------------------------------------------------------
# Description: Demonstrates how to plot a line on any map
# projection using the Macro Library function
# mvl_geoline.
# ---------------------------------------------------------------
import metview as mv
# set up the shaded coastlines
land_sea_shade = mv.mcoast(
map_coastline_land_shade = "on",
map_coastline_land_shade_colour = "RGB(0.98,0.95,0.82)",
map_coastline_sea_shade = "on",
map_coastline_sea_shade_colour = "RGB(0.85,0.93,1)"
)
# define the geographic view
view = mv.geoview(
map_projection = "polar_stereographic",
map_area_definition = "corners",
area = [-5,-30,10,84], # S,W,N,E
coastlines = land_sea_shade
)
# create a geoline broken into 1-degree segments
line_increment_in_degrees = 1
# coordinates of line end-points given as lat1,lon1,lat2,lon2
geoline = mv.mvl_geoline(55, -22, 5, 45, line_increment_in_degrees)
# define the plotting attributes for the line
line_visdef = mv.mgraph(
graph_line_colour = "red",
graph_line_thickness = "4",
graph_line_style = 'dash'
)
# define the output plot file
mv.setoutput(mv.pdf_output(output_name = 'geoline_on_map'))
# plot the line on the map
mv.plot(view, geoline, line_visdef)