#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""
Created on Wed Nov 22 14:04:14 2017

@author: dandrea
"""

import matplotlib.pyplot as plt
import numpy as np    
import cartopy.crs as ccrs


def cylmap(lat,lon,field, *args, **kwargs):

    
    ''' Plots a contour map of the array in "field" over a map of the Earth with coastlines
        and latitude longitude grid. Contours are couloured and filled, a colorbar is shown.
        
        "lat" and "lon" are vectors specifying the latitude and longitude of the map. 
        They must have dimensions compatible with "field". 
        
        Optional parameters:
            levels : array_like
                an array containing the contour levels for the map, 
                default is nlev levels between the minimum 
                and the maximum of field
            nlev   : int
                number of levels, default 10, if levels is specified, nlev is overridden
            title  : str
                plot title, default "no title"
            
  
      '''

    title = kwargs.get('title',"")
    nlev  = kwargs.get('nlev',10)

    plt.figure(figsize=(10, 8))
    ax = plt.axes(projection=ccrs.PlateCarree())
    ax.set_extent([lon[1], lon[-1], lat[1], lat[-1]], crs=ccrs.PlateCarree())
    ax.coastlines()
    ax.gridlines()
    x,y=np.meshgrid(lon, lat)
    
    lev=(np.linspace((field.min()), (field.max()),nlev))  # DEFAULT LEVELS

    lev = kwargs.get('levels',lev)

    plt.contourf(x,y,field,transform=ccrs.PlateCarree(),cmap=plt.cm.jet, levels=lev)
    plt.colorbar(shrink=.5)  # draw colorbar
    plt.contour(x,y,field,transform=ccrs.PlateCarree(),colors='k', levels=lev)
    if title : plt.title(title)