selected numeric data before correlation
- [x] closes #18570
- [x] tests added / passed
- [ ] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

I select the numeric data before the calculation happens with a Series.

No whatsnew entry yet.
actually do this for 0.22 # [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/18651?src=pr&el=h1) Report
> Merging [#18651](https://codecov.io/gh/pandas-dev/pandas/pull/18651?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/6b6cfb84ed37c94cbae54e89437c14fe84cbdc4f?src=pr&el=desc) will **decrease** coverage by `0.02%`.
> The diff coverage is `100%`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/18651/graphs/tree.svg?token=eZ4WkYLtcO&src=pr&height=150&width=650)](https://codecov.io/gh/pandas-dev/pandas/pull/18651?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #18651      +/-   ##
==========================================
- Coverage    91.6%   91.57%   -0.03%     
==========================================
  Files         153      153              
  Lines       51250    51221      -29     
==========================================
- Hits        46947    46908      -39     
- Misses       4303     4313      +10
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `89.44% <100%> (-0.01%)` | :arrow_down: |
| #single | `40.67% <0%> (-0.11%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/18651?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/core/frame.py](https://codecov.io/gh/pandas-dev/pandas/pull/18651/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `97.81% <100%> (-0.1%)` | :arrow_down: |
| [pandas/io/gbq.py](https://codecov.io/gh/pandas-dev/pandas/pull/18651/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL2dicS5weQ==) | `25% <0%> (-58.34%)` | :arrow_down: |
| [pandas/stats/moments.py](https://codecov.io/gh/pandas-dev/pandas/pull/18651/diff?src=pr&el=tree#diff-cGFuZGFzL3N0YXRzL21vbWVudHMucHk=) | `70.81% <0%> (-0.39%)` | :arrow_down: |
| [pandas/core/window.py](https://codecov.io/gh/pandas-dev/pandas/pull/18651/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvd2luZG93LnB5) | `96.31% <0%> (-0.07%)` | :arrow_down: |
| [pandas/tseries/offsets.py](https://codecov.io/gh/pandas-dev/pandas/pull/18651/diff?src=pr&el=tree#diff-cGFuZGFzL3RzZXJpZXMvb2Zmc2V0cy5weQ==) | `96.86% <0%> (-0.04%)` | :arrow_down: |

------

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> Powered by [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/18651?src=pr&el=footer). Last update [6b6cfb8...dcc66ea](https://codecov.io/gh/pandas-dev/pandas/pull/18651?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 thanks!