I have 3 different numpy arrays, but they all start with two columns which contain the day of year and the time. For example:

```
   dyn = [[  83   12   7.10555687e-01 ...,   6.99242766e-01   6.868761e-01]
         [  83   13   8.28091972e-01 ...,   8.33734118e-01   8.47266838e-01]
         [  83   14   8.79437354e-01 ...,   8.73598144e-01   8.57156213e-01]
         [  161   23   3.28109488e-01 ...,   2.83043689e-01  2.59775391e-01]
         [  162   0    2.23502046e-01 ...,   1.96972086e-01  1.65565263e-01]
         [  162   1   2.51653976e-01 ...,   2.17209188e-01   1.42133495e-1]]

   us = [[  133   18   3.00483815e+02 ...,   1.94277561e+00   2.8168959e+00]
        [  133   19   2.98832620e+02 ...,   2.42506475e+00   2.99730800e+00]
        [  133   20   2.96706105e+02 ...,   3.16851622e+00   4.41187088e+00]
        [  161   23   2.88336560e+02 ...,   3.44864070e-01   3.85055635e-01]
        [  162   0    2.87593240e+02 ...,   2.93002410e-01   2.67112490e-01]
        [  162   2    2.86992180e+02 ...,   7.08996730e-02   2.6403210e-01]]

```

I need to be able to remove any rows where specific date and time isn't present in all 3 arrays. In other words, so I'm left with 3 arrays where the first 2 columns are identical in each of the 3 arrays. 

So the resulting smaller arrays would be: 

```
dyn= [[  161   23   3.28109488e-01 ...,   2.83043689e-01  2.59775391e-01]
     [  162   0    2.23502046e-01 ...,   1.96972086e-01  1.65565263e-01]]

us= [[  161   23   2.88336560e+02 ...,   3.44864070e-01   3.85055635e-01]
    [  162   0    2.87593240e+02 ...,   2.93002410e-01   2.67112490e-01]]

```

(But then also limited by what's in the third array)

I've tried using sort/zip but not sure that it should be applied to 2D array like that:

```
X= dyn
Y = us
xsorted=[x for (y,x) in sorted(zip(Y[:,1],X[:,1]), key=lambda pair: pair[0])]

```

And also a loop but that only works when the same times/days are in the same position within the array, which isn't helpful

```
for i in range(100):
     dyn_small=dyn[dyn[:,0]==us[i,0]]

```