Hello Guys, How are you all? Hope You all Are Fine. Today We Are Going To learn about **How to create a numpy array of lists** **in Python**. So Here I am Explain to you all the possible Methods here.

Without wasting your time, Let’s start This Article.

Table of Contents

## How to create a numpy array of lists?

**How to create a numpy array of lists?**If you really need a 1-d array of lists you will have to wrap your lists in your own class as numpy will always try to convert your lists to arrays inside of an array (which is more efficient but obviously requires constant size-elements)

**create a numpy array of lists**If you really need a 1-d array of lists you will have to wrap your lists in your own class as numpy will always try to convert your lists to arrays inside of an array (which is more efficient but obviously requires constant size-elements)

## Method 1

If you really need a 1-d array of lists you will have to wrap your lists in your own class as numpy will always try to convert your lists to arrays inside of an array (which is more efficient but obviously requires constant size-elements), for example through

class mylist: def __init__(self, l): self.l=l def __repr__(self): return repr(self.l) def append(self, x): self.l.append(x)

and then you can change any element without changing the dimension of others

>>> x = mylist([1,2,3]) >>> y = mylist([1,2,3]) >>> import numpy as np >>> data = np.array([x,y]) >>> data array([[1,2,3], [1,2,3]], dtype=object) >>> data[0].append(2) >>> data array([[1,2,3,2], [1,2,3]], dtype=object)

### Update

As suggested by `ali_m`

there is actually a way to force numpy to simply create a 1-d array for references and then feed them with actual lists

>>> data = np.empty(2, dtype=np.object) >>> data[:] = [1, 2, 3], [1, 2, 3] >>> data array([[1, 2, 3], [1, 2, 3]], dtype=object) >>> data[0].append(4) >>> data array([[1, 2, 3, 4], [1, 2, 3]], dtype=object)

## Method 2

data = np.empty(20, dtype=np.object) for i in range(data.shape[0]): data[i] = [] data[i].append(i) print(data)

The result will be:

[list([0]) list([1]) list([2]) list([3]) list([4]) list([5]) list([6]) list([7]) list([8]) list([9]) list([10]) list([11]) list([12]) list([13]) list([14]) list([15]) list([16]) list([17]) list([18]) list([19])]

**Conclusion**

It’s all About this issue. Hope all Methods helped you a lot. Comment below Your thoughts and your queries. Also, Comment below which Method worked for you? Thank You.

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