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I have two lists `A`

and `B`

. I am removing element from `A`

which is less than `tol`

. But I also want to remove element from `B`

corresponding to the removed element from `A`

. For example, `[[2.22105075e-18]]`

was removed from `A`

. Corresponding to this, `[[4,13]]`

should be removed from `B`

. I present the current and expected output.

```
import numpy as np
A= [[9.16435586e-05], [0.000184193464], [9.28353239e-05], [2.22105075e-18]]
B= [[13, 14], [4, 5], [5, 14], [4, 13]]
tol=1e-12
CA=[[x[0]] for x in A if x[0]>tol]
CB=[x for x,y in enumerate(CA) if list(y) in B]
print(CB)
```

The current output is

```
[]
```

The expected output is

```
[[13, 14], [4, 5], [5, 14]]
```

### >Solution :

You could process the two in parallel with `zip`

:

```
CA, CB = map(list, zip(*((a, b) for a, b in zip(A, B) if a[0]>tol)))
# or
# CA, CB = map(list, zip(*(x for x in zip(A, B) if x[0][0]>tol)))
```

Output:

```
# CA
[[9.16435586e-05], [0.000184193464], [9.28353239e-05]]
# CB
[[13, 14], [4, 5], [5, 14]]
```