在 Basemap 上绘制 netCDF4 数据

Question

I have a csv file with 3 columns ( longitude , latitude and precipitation ) and 90 rows and I need to plot it as a map in Python. I have not a time index, only value associated with coordinates. I have followed this procedure:

1. Convert.cvs to.nc (netCDF file)
2. Plot.nc thought Basemap + Matplotlib

In the second step, I got the follow error:

ValueError: need more than 1 value to unpack

Which seems to be in line c_scheme = mp.pcolor(x,y,avp[:], cmap = 'jet') from the code, especially avp[:] . When I run avp.shape I get it have a shape of (90L,) and avp.ndim show a value of 1.

My questions are: What values should be displayed in "avp" exactly? What should I extract from this dimension?

from netCDF4 import Dataset
import numpy as np
import matplotlib.pyplot as plt
from mpl_toolkits.basemap import Basemap

data = Dataset(r'SN1_PTPM.nc')

fig = plt.figure(figsize=(12,9))

lats = data.variables['Latitude'][:] #latitute column
lons = data.variables['Longitude'][:] #longitute column
avp = data.variables['Precipitation'][:] #precipitation column

mp = Basemap(projection = 'merc',
            llcrnrlon = 5.5,
            llcrnrlat = 8.5,
            urcrnrlon = -75,
            urcrnrlat = -72,
            resolution = 'i')

lon,lat = np.meshgrid(lons,lats)
x,y = mp(lon,lat)

c_scheme = mp.pcolor(x,y,avp[:], cmap = 'jet')
cbar = mp.colorbar(c_scheme, location = 'right', pad = '10%')

plt.show()

I thank you in advance for any information you can give me.

Answer 1

I imagine the issue is your coordinates are tuples (lat,lon) associated with one value each. In that case you can't use meshgrid because that will create a grid of coordinates but you don't have values at all of those points (you create a 2 dimensional grid but only have a 1 dimensional list of values)