# Convert NumPy array to Python list

## Question:

How do I convert a NumPy array into a Python List?

## Answers:

Use `tolist()`

:

```
>>> import numpy as np
>>> np.array([[1,2,3],[4,5,6]]).tolist()
[[1, 2, 3], [4, 5, 6]]
```

Note that this converts the values from whatever numpy type they may have (e.g. np.int32 or np.float32) to the "nearest compatible Python type" (in a list). If you want to preserve the numpy data types, you could call list() on your array instead, and you’ll end up with a list of numpy scalars. (Thanks to Mr_and_Mrs_D for pointing that out in a comment.)

The numpy .tolist method produces nested lists if the numpy array shape is 2D.

if flat lists are desired, the method below works.

```
import numpy as np
from itertools import chain
a = [1,2,3,4,5,6,7,8,9]
print type(a), len(a), a
npa = np.asarray(a)
print type(npa), npa.shape, "n", npa
npa = npa.reshape((3, 3))
print type(npa), npa.shape, "n", npa
a = list(chain.from_iterable(npa))
print type(a), len(a), a`
```

`tolist()`

works fine even if encountered a nested array, say a pandas `DataFrame`

;

```
my_list = [0,1,2,3,4,5,4,3,2,1,0]
my_dt = pd.DataFrame(my_list)
new_list = [i[0] for i in my_dt.values.tolist()]
print(type(my_list),type(my_dt),type(new_list))
```

```
c = np.array([[1,2,3],[4,5,6]])
list(c.flatten())
```

Another option

```
c = np.array([[1,2,3],[4,5,6]])
c.ravel()
#>> array([1, 2, 3, 4, 5, 6])
# or
c.ravel().tolist()
#>> [1, 2, 3, 4, 5, 6]
```

also works.

The easiest way to convert array to a list is using the numpy package:

```
import numpy as np
#2d array to list
2d_array = np.array([[1,2,3],[8,9,10]])
2d_list = 2d_array.tolist()
```

To check the data type, you can use the following:

```
type(object)
```