# 'list' object has no attribute 'shape'

## Question:

how to create an array to numpy array?

```
def test(X, N):
[n,T] = X.shape
print "n : ", n
print "T : ", T
if __name__=="__main__":
X = [[[-9.035250067710876], [7.453250169754028], [33.34074878692627]], [[-6.63700008392334], [5.132999956607819], [31.66075038909912]], [[-5.1272499561309814], [8.251499891281128], [30.925999641418457]]]
N = 200
test(X, N)
```

I am getting error as

```
AttributeError: 'list' object has no attribute 'shape'
```

So, I think I need to convert my X to numpy array?

## Answers:

Use `numpy.array`

to use `shape`

attribute.

```
>>> import numpy as np
>>> X = np.array([
... [[-9.035250067710876], [7.453250169754028], [33.34074878692627]],
... [[-6.63700008392334], [5.132999956607819], [31.66075038909912]],
... [[-5.1272499561309814], [8.251499891281128], [30.925999641418457]]
... ])
>>> X.shape
(3L, 3L, 1L)
```

**NOTE** `X.shape`

returns 3-items tuple for the given array; `[n, T] = X.shape`

raises `ValueError`

.

```
import numpy
X = numpy.array(the_big_nested_list_you_had)
```

It’s still not going to do what you want; you have more bugs, like trying to unpack a 3-dimensional shape into two target variables in `test`

.

list object in python does not have ‘shape’ attribute because ‘shape’ implies that all the columns (or rows) have equal length along certain dimension.

Let’s say list variable a has following properties:

```
a = [[2, 3, 4]
[0, 1]
[87, 8, 1]]
```

it is impossible to define ‘shape’ for variable ‘a’.

That is why ‘shape’ might be determined only with ‘arrays’ e.g.

```
b = numpy.array([[2, 3, 4]
[0, 1, 22]
[87, 8, 1]])
```

I hope this explanation clarifies well this question.

Alternatively, you can use `np.shape(...)`

For instance:

```
import numpy as np
a=[1,2,3]
```

and `np.shape(a)`

will give an output of `(3,)`

If the type is list, use `len(list)`

and `len(list[0])`

to get the row and column.

```
l = [[1,2,3,4], [0,1,3,4]]
```

`len(l)`

will be 2.

`len(l[0])`

will be 4.

Firstly you have to import numpy library (refer code for making a numpy array).

`shape`

only gives the output only if the variable is attribute of numpy library. In other words it must be a np.array or any other data structure of numpy.

E.g.

```
import numpy
a=numpy.array([[1,1],[1,1]])
a.shape
```

```
(2, 2)
```

İf you have list, you can print its shape as if it is converted to array

```
import numpy as np
print(np.asarray(X).shape)
```