# [Numpy-discussion] Array as Variable using "from cdms2 import MV2 as MV"

josef.pktd at gmail.com josef.pktd at gmail.com
Mon Apr 25 03:17:42 EDT 2011

```On Mon, Apr 25, 2011 at 2:50 AM, dileep kunjaai <dileepkunjaai at gmail.com> wrote:
> Dear sir,
>
>      I am have 2  mxn numpy array say "obs" & "fcst". I have to
> calculate     sum of squre of (obs[i, j]-fcst[i, j]) using     from cdms2
> import MV2 as MV   in CDAT without using "for"  loop.
>
> For example:
> obs=
> [0.6    1.1    0.02    0.2   0.2
> 0.8    0.    0.    0.4   0.8
> 0.5    5.5    1.5    0.5   1.5
> 3.5    0.5    1.5    5.0   2.6
> 5.1    4.1    3.2    2.3   1.5
> 4.4    0.9    1.5    2.    2.3
> 1.1    1.1    1.5    12.6  1.3
> 2.2    12    1.7    1.6   15
> 1.9    1.5    0.9    2.5   5.5 ]
>
>
>
> fcst=
>
> [0.7    0.1    0.2    0.2   0.2
> 0.3    0.8    0.    0.    0.
> 0.5    0.5    0.5    0.5   0.5
> 0.7    1.     1.5    2.    2.6
> 5.1    4.1    3.2    2.3   1.5
> 0.7    1.    1.5    2.    2.3
> 1.1    1.1    1.1    12.7  1.3
> 2.2    2.    1.7    1.6   1.5
> 1.9    1.5    0.9    0.5   7.5]
>
> here "obs" and "fcst" are numpy array
> I give
>
> obs=MV.array(obs)
> fcst=MV.array(fcst)
>
> Then it become
>
>
> sbst=obs-fcst
>
>>> subst=
> [[ -0.1    1.    -0.18   0.     0.  ]
>  [  0.5   -0.8    0.     0.4    0.8 ]
>  [  0.     5.     1.     0.     1.  ]
>  [  2.8   -0.5    0.     3.     0.  ]
>  [  0.     0.     0.     0.     0.  ]
>  [  3.7   -0.1    0.     0.     0.  ]
>  [  0.     0.     0.4   -0.1    0.  ]
>  [  0.    10.     0.     0.    13.5 ]
>  [  0.     0.     0.     2.    -2.  ]]
>
> But i dont know how to find sum of squre of each term....(Actually my aim is
> to finding MEAN SQUARED ERROR)

(sbst**2).sum()

or with sum along columns
(sbst**2).sum(0)

explanation is in the documentation

Josef

>
>
>
>
> Thanking you...................
>
> --
> DILEEPKUMAR. R
> J R F, IIT DELHI
>
>
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>
>
```