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POHow to create a smaller array from a larger array python
 

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  1. POHow to create a smaller array from a larger array python
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    <p>I have a large 4D data set and need to create a smaller 4D array from it. I am fairly new to python and am use to IDL or matlab. I read in my values then using the where function I find the index numbers I need for each dimension from smaller 1D arrays. I am trying to create a new array from these index numbers but I keep getting the shape mismatch error (can not be broacast to a single shape.</p> <pre><code>import numpy as n import matplotlib.pyplot as plt import Scientific.IO.NetCDF as S file=S.NetCDFFile('wspd.mon.mean.nc',mode='r') #Opening File Lat=file.variables['lat'].getValue() # Reading in the latitude variables, 73 Lon=file.variables['lon'].getValue() # Reading in the longitude variables, 144 Level=file.variables['level'].getValue() # Reading in the levels, 17 of them Defaulttime=file.variables['time'].getValue() # Reading in the time, hrs since 1-1-1 Defaultwindspeed=file.variables['wspd'].getValue() # Reading in the windspeed(time, level, lat, lon) Time=n.arange(len(Defaulttime))/12.+1948 #Creates time array into readable years with 12 months goodtime=n.where((Time&gt;=1948)&amp;(Time&lt;2013)) #Creates a time array for the years that I want, 1948-2012, since 2013 only has until October, I will not be using that data. goodlat=n.where((Lat&gt;=35)&amp;(Lat&lt;=50)) #Latitudes where the rockies and plains are in the US plainslon=n.where((Lon&gt;=275)&amp;(Lon&lt;=285)) Windspeedsplains=Defaultwindspeed[goodtime,:,goodlat,plainslon] </code></pre> <p>The error below is generated by the line above (last line of code).</p> <pre><code>&gt;&gt;&gt;ValueError: shape mismatch: objects cannot be broadcast to a single shape </code></pre>
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    1. COi doubt anyone will be able to help you with a question that looks like this. The least you could do is figure out which line is actually failing
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    2. COIs `Defaultwindspeed` actually 4D? Use `Defaultwindspeed.shape` or `Defaultwindspeed.ndim` to check...
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    3. CO@atomh33ls it must be, otherwise the error would be `too many indices`. I think the problem is in the shapes of `goodtime`, `goodlat`, and `plainslon`. @Cwilliams, what do you get if you print `goodtime.shape, goodlat.shape, plainslon.shape`?
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