id,node_id,number,title,user,state,locked,assignee,milestone,comments,created_at,updated_at,closed_at,author_association,active_lock_reason,draft,pull_request,body,reactions,performed_via_github_app,state_reason,repo,type
1599044689,I_kwDOAMm_X85fT3xR,7558,shift time using frequency strings,2448579,open,0,,,2,2023-02-24T17:35:52Z,2023-02-26T15:08:13Z,,MEMBER,,,,"### Discussed in https://github.com/pydata/xarray/discussions/7557

<div type='discussions-op-text'>

<sup>Originally posted by **arfriedman** February 24, 2023</sup>
Hi,

In addition to integer offsets, I was wondering if it is possible to [shift](https://docs.xarray.dev/en/stable/generated/xarray.Variable.shift.html) a variable by a specific time frequency interval as in [pandas](https://pandas.pydata.org/docs/reference/api/pandas.Series.shift.html).

For example, something like:
```
import xarray as xr
ds = xr.tutorial.load_dataset(""air_temperature"")
air = ds[""air""]
air.shift(time=""1D"")

```
Otherwise, is there another xarray function or recommended approach for this type of operation?</div>","{""url"": ""https://api.github.com/repos/pydata/xarray/issues/7558/reactions"", ""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,,13221727,issue
1599056009,I_kwDOAMm_X85fT6iJ,7559,Support specifying chunk sizes using labels (e.g. frequency string),2448579,open,0,,,2,2023-02-24T17:44:03Z,2023-02-25T03:46:49Z,,MEMBER,,,,"### Is your feature request related to a problem?

`dask.dataframe` [supports](https://docs.dask.org/en/stable/generated/dask.dataframe.DataFrame.repartition.html) repartitioning or rechunking using a frequency string (`freq` kwarg).

I think this would be a useful addition to `.chunk`. It would help with some groupby problems ([as suggested in this comment](https://github.com/pydata/xarray/issues/2237#issuecomment-398581618)) and generally make a few problems amenable to blockwise/map_blocks solutions.

### Describe the solution you'd like

1. One solution is to allow `.chunk(lon=5, time=""MS"")`. There is some ugliness in that this syntax mixes up integer index values (`lon=5`) and a label-based frequency string `time=""MS""`
2. So perhaps a second method `chunk_by_labels` would be useful where `chunk_by_labels(lon=5, time=""MS"")` would rechunk the data so that a single chunk contains 5° of longitude points and a month of time. Alternative this could be `.chunk(lon=5, time=""MS"", by=""labels"")`

### Describe alternatives you've considered

Have the user do this manually but that's kind of annoying, and a bit advanced.

### Additional context

_No response_","{""url"": ""https://api.github.com/repos/pydata/xarray/issues/7559/reactions"", ""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,,13221727,issue