python - 使用 basemap 和python在 map 上绘制海洋

我在这里绘制可用的netCDF文件:
https://goo.gl/QyUI4J

使用下面的代码， map 如下所示:


但是，我希望海洋呈白色。更好的是，我希望能够指定海洋显示为哪种颜色。如何更改下面的代码来做到这一点？目前，问题在于海洋正在数据规模上标绘。 (请注意，netCDF文件的大小约为3.5 GB)。

import pdb, os, glob, netCDF4, numpy
from matplotlib import pyplot as plt
from mpl_toolkits.basemap import Basemap

def plot_map(path_nc, var_name):
    """
    Plot var_name variable from netCDF file
    :param path_nc: Name of netCDF file
    :param var_name: Name of variable in netCDF file to plot on map
    :return: Nothing, side-effect: plot an image
    """

    nc = netCDF4.Dataset(path_nc, 'r', format='NETCDF4')
    tmax  = nc.variables['time'][:]

    m = Basemap(projection='robin',resolution='c',lat_0=0,lon_0=0)

    m.drawcoastlines()
    m.drawcountries()

    # find x,y of map projection grid.
    lons, lats = get_latlon_data(path_nc)
    lons, lats = numpy.meshgrid(lons, lats)
    x, y = m(lons, lats)
    nc_vars = numpy.array(nc.variables[var_name])

    # Plot!
    m.drawlsmask(land_color='white',ocean_color='white')
    cs = m.contourf(x,y,nc_vars[len(tmax)-1,:,:],numpy.arange(0.0,1.0,0.1),cmap=plt.cm.RdBu)

    # add colorbar
    cb = m.colorbar(cs,"bottom", size="5%", pad='2%')
    cb.set_label('Land cover percentage '+var_name+' in '+os.path.basename(path_nc))

    plt.show()


plot_map('perc_crops.nc','LU_Corn.nc')

最佳答案

您需要在maskoceans数据集上使用 nc_vars
在contourf之前，插入

nc_new = maskoceans(lons,lats,nc_vars[len(tmax)-1,:,:])

然后使用新屏蔽的数据集调用contourf，即

cs = m.contourf(x,y,nc_new,numpy.arange(0.0,1.0,0.1),cmap=plt.cm.RdBu)

要确定海洋的颜色，您可以将调用调至drawslmask(如果您要使用白色海洋)，也可以在该调用中指定海洋的颜色-例如插入m.drawlsmask(land_color='white',ocean_color='cyan')。
我在下面给出了对您的修改尽可能少的工作代码。取消对drawslmask的调用的注释，以查看青绿色的海洋。
输出

完整的工作版本的代码

import pdb, os, glob, netCDF4, numpy
from matplotlib import pyplot as plt
from mpl_toolkits.basemap import Basemap, maskoceans

def plot_map(path_nc, var_name):
    """
    Plot var_name variable from netCDF file
    :param path_nc: Name of netCDF file
    :param var_name: Name of variable in netCDF file to plot on map
    :return: Nothing, side-effect: plot an image
    """

    nc = netCDF4.Dataset(path_nc, 'r', format='NETCDF4')
    tmax  = nc.variables['time'][:]

    m = Basemap(projection='robin',resolution='c',lat_0=0,lon_0=0)

    m.drawcoastlines()
    m.drawcountries()

    # find x,y of map projection grid.
    lons, lats = nc.variables['lon'][:],nc.variables['lat'][:]
    # N.B. I had to substitute the above for unknown function get_latlon_data(path_nc)
    # I guess it does the same job

    lons, lats = numpy.meshgrid(lons, lats)
    x, y = m(lons, lats)
    nc_vars = numpy.array(nc.variables[var_name])

    #mask the oceans in your dataset
    nc_new = maskoceans(lons,lats,nc_vars[len(tmax)-1,:,:])

    #plot!
    #optionally give the oceans a colour with the line below
    #Note - if land_color is omitted it will default to grey
    #m.drawlsmask(land_color='white',ocean_color='cyan')
    cs = m.contourf(x,y,nc_new,numpy.arange(0.0,1.0,0.1),cmap=plt.cm.RdBu)

    # add colorbar
    cb = m.colorbar(cs,"bottom", size="5%", pad='2%')
    cb.set_label('Land cover percentage '+var_name+' in '+os.path.basename(path_nc))

    plt.show()


plot_map('perc_crops.nc','LU_Corn.nc')

P.S. 这是要测试的大文件!

关于python - 使用 basemap 和python在 map 上绘制海洋，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/31996071/