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POPlotting currents data on a map : Too many value to unpack error
 

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  1. POPlotting currents data on a map : Too many value to unpack error
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    <p>So here is my code : </p> <pre><code>from netCDF4 import * import datetime as dt import numpy as np import numpy.ma as ma from datetime import date, datetime, timedelta import matplotlib.pyplot as plt nc=Dataset('datasets/essai.nc') time_var = nc.variables[str('forecast_time0')] wave_var = nc.variables['DIST_GDS0_SFC'] lat = nc.variables['g0_lat_1'][:] lon = nc.variables['g0_lon_2'][:] uin = nc.variables['UOGRD_GDS0_DBSL'][:] vin = nc.variables['VOGRD_GDS0_DBSL'][:] plt.quiver(lon[::5], lat[::5], uin[::5], vin[::5], scale=200) </code></pre> <p>And here is the error I get : </p> <pre><code>Traceback (most recent call last): File "nctry.py", line 37, in &lt;module&gt; plt.quiver(lon[::5], lat[::5], uin[::5], vin[::5], scale=200) File "C:\Python27\lib\site-packages\matplotlib\pyplot.py", line 2877, in quive r ret = ax.quiver(*args, **kw) File "C:\Python27\lib\site-packages\matplotlib\axes.py", line 6627, in quiver q = mquiver.Quiver(self, *args, **kw) File "C:\Python27\lib\site-packages\matplotlib\quiver.py", line 394, in __init __ X, Y, U, V, C = _parse_args(*args) File "C:\Python27\lib\site-packages\matplotlib\quiver.py", line 356, in _parse _args nr, nc = U.shape ValueError: too many values to unpack </code></pre> <p>I think the problem comes from the UOGRD and VOGRD which has many values but don't know how manipulate it?</p> <p>Here is how uogrd looks like : <img src="https://i.stack.imgur.com/JEEVM.jpg" alt="UOGRD "></p> <p>the forecast_time up as far as a number of 4.</p> <p>Ok so I used the np.array and shape functions, here is what i've got : </p> <blockquote> <p>C:\Python27>python nctry.py (321,) //lat (720,) //lon (4, 321, 720) //uogrd (4, 321, 720) //vogrd</p> </blockquote> <p>Then I tried this code :</p> <p><img src="https://i.stack.imgur.com/P2PDM.jpg" alt="code"></p> <p>but it only shows one arrow. Can you tell me why?</p> <p>So now I have some modelling which looks like this : <img src="https://i.stack.imgur.com/NvZ9Q.jpg" alt="currents modelized"></p> <p>But this image doesn't change, for [0, :, :], 1, 2 or 3.. What's wrong? Furthermore, all the arrows are going to the same direction, not really true when we're talking about currents' ocean. I use the deg2rad function. Finally, I can't imagine the coastlines, is that normal? Thank you</p>
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    1. COPerhaps display some of what `U0GRID` looks like. I am having trouble installing the netCDF4 package, so I can't look at the dataset myself. Perhaps you could convert the `lat`, `lon`, etc. lists to `np.array`s then print out `.shape` of each array so we can see the dimensionality
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