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What is the difference between np.array() and np.asarray()?

What is the difference between NumPy's np.array and np.asarray? When should I use one rather than the other? They seem to generate identical output.

Answer*

### Difference

1. `np.array()`: Converts input data like list, tuple, etc. to `ndarray` and **copies the input data by default**. This creates redundant object in memory.
2. `np.asarray()`: Converts input data to `ndarray` but **does not copy if the input is already `ndarray`**. This is more memory efficient.

```python
import numpy as np

print("NumPy version:", np.__version__)
```

```
NumPy version: 1.22.3
```

### Case 1: Using `np.array()` when input is `ndarray`.

```python
# STEP 1: Initialize source.
src1 = np.ones(5)
print("Data type:", type(src1))
print("Values:\n", src1)

# STEP 2: Convert to `ndarray`.
arr1 = np.array(src1)               # np.array() is used.
print("\nData type:", type(arr1))
print("Values:\n", arr1)

# STEP 3: Compare source with converted `ndarray`.
print("\nIs Source & new NumPy array same?\n", src1 is arr1)
```

#### Output

```text
Data type: <class 'numpy.ndarray'>
Values:
 [1. 1. 1. 1. 1.]

Data type: <class 'numpy.ndarray'>
Values:
 [1. 1. 1. 1. 1.]

Is Source & new NumPy array same?
 False
```

### Case 2: Using `np.asarray()` when input is `ndarray`.

```python
# STEP 1: Initialize source.
src2 = np.ones(5)
print("Data type:", type(src2))
print("Values:\n", src2)

# STEP 2: Convert to `ndarray`.
arr2 = np.asarray(src2)             # np.asarray() is used.
print("\nData type:", type(arr2))
print("Values:\n", arr2)

# STEP 3: Compare source with converted `ndarray`.
print("\nIs Source & new NumPy array same?\n", src2 is arr2)
```

#### Output

```text
Data type: <class 'numpy.ndarray'>
Values:
 [1. 1. 1. 1. 1.]

Data type: <class 'numpy.ndarray'>
Values:
 [1. 1. 1. 1. 1.]

Is Source & new NumPy array same?
 True
```

Hence by comparing two outputs we can conclude that:  
When using `np.asarray()` on `ndarray`, the source `ndarray` and converted `ndarray` are **pointing to same object in the memory**.

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What is the difference between np.array() and np.asarray()?

Answer*