jxu

`corr` with ignoring null values

3

### Description With the corrent [polars.DataFrame.corr](https://pola-rs.github.io/polars/py-polars/html/reference/dataframe/api/polars.DataFrame.corr.html#polars.DataFrame.corr), it returns nulls when columns contain nulls. Sometimes, ignoring nulls could be a wanted option. Pandas has [pandas.DataFrame.corr](https://pandas.pydata.org/docs/reference/api/pandas.DataFrame.corr.html#pandas-dataframe-corr).

#### ALL software version info (this library, plus any other relevant software, e.g. bokeh, python, notebook, OS, browser, etc) bokeh: 3.4.3 Python: 3.12.4 OS: linux ubuntu 24.04 vscode: 1.92.0 jupyter(extension...