# Gridding only a single sweep(90 degree)of a PPI scan data using PYART

**URL:** <https://openradar.discourse.group/t/gridding-only-a-single-sweep-90-degree-of-a-ppi-scan-data-using-pyart/200>\
**Category:** Python\
**Tags:** py-art\
**Created:** [March 27, 2023, 1:40pm UTC](https://openradar.discourse.group/t/gridding-only-a-single-sweep-90-degree-of-a-ppi-scan-data-using-pyart/200 "2023-03-27T13:40:24Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Mehzooz](https://avatars.discourse-cdn.com/v4/letter/m/a88e57/32.png) [@Mehzooz](https://openradar.discourse.group/u/Mehzooz)\
**Post date:** [March 27, 2023, 1:40pm UTC](https://openradar.discourse.group/t/gridding-only-a-single-sweep-90-degree-of-a-ppi-scan-data-using-pyart/200/1 "2023-03-27T13:40:24Z")

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I needed to check the terminal velocity of hydrometeors at 5 and 3 kilometres. Inorder to do that I have an X band radar PPI data. **I needed the data only at 90 degrees so that it gives a zenith looking data and this could give me terminal fall velocity**. But i dont know how to grid only a single sweep(90 degree) so that I can get the CAPPI at 5 and 3 kms without the influence of other elevations.Is there anyway I can grid only one sweep?

Thank you in advance

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**Author:** ![mgrover1](https://yyz2.discourse-cdn.com/free1/user_avatar/openradar.discourse.group/mgrover1/32/7_2.png) [@mgrover1](https://openradar.discourse.group/u/mgrover1)\
**Post date:** [March 28, 2023, 1:15pm UTC](https://openradar.discourse.group/t/gridding-only-a-single-sweep-90-degree-of-a-ppi-scan-data-using-pyart/200/2 "2023-03-28T13:15:27Z")

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> [@Mehzooz](#):
>
> needed to check the terminal velocity of hydrometeors at 5 and 3 kilometres. Inorder to do that I have an X band radar PPI data. **I needed the data only at 90 degrees so that it gives a zenith looking data and this could give me terminal fall velocity**. But i dont know how to grid only a single sweep(90 degree) so that I can get the CAPPI at 5 and 3 kms without the influence of other elevations.Is there anyway I can grid only one sweep?

I would suggest using the extract sweeps option to pull out the single sweep you want to work with… if you know it is the **last sweep** , then it might look something like

```python
# Extract the last sweep
subset = radar.extract_sweeps([-1])

# Grid your radar
grid = ...(subset)

```

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**Author:** ![Mehzooz](https://avatars.discourse-cdn.com/v4/letter/m/a88e57/32.png) [@Mehzooz](https://openradar.discourse.group/u/Mehzooz)\
**Post date:** [March 28, 2023, 7:40pm UTC](https://openradar.discourse.group/t/gridding-only-a-single-sweep-90-degree-of-a-ppi-scan-data-using-pyart/200/3 "2023-03-28T19:40:35Z")

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Thank you sir. It works. Really appreciate your help