actually, the Pythonic way of doing this would be:

```python
for r, nr in zip(radius, n):
    radius_stretched.extend([r] * nr)
```

In fact, I would rename your arrays `radius` --> `radii`, `n` --> `ns`, and write:

```python
for radius, n in zip(radii, ns):
    radii_stretched.extend([radius] * n)
```