html_url,issue_url,id,node_id,user,created_at,updated_at,author_association,body,reactions,performed_via_github_app,issue
https://github.com/pydata/xarray/pull/7840#issuecomment-1547169473,https://api.github.com/repos/pydata/xarray/issues/7840,1547169473,IC_kwDOAMm_X85cN-7B,43316012,2023-05-15T04:15:53Z,2023-05-15T04:15:53Z,COLLABORATOR,"Well that's the point, ""x"" is a dimension as well as a coordinate. And since dimensions are names you cannot assign anything to them.
If you want you can change coordinate by dimension coordinate.","{""total_count"": 1, ""+1"": 1, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,1707774178
https://github.com/pydata/xarray/pull/7840#issuecomment-1546939363,https://api.github.com/repos/pydata/xarray/issues/7840,1546939363,IC_kwDOAMm_X85cNGvj,43316012,2023-05-14T16:29:13Z,2023-05-14T16:29:13Z,COLLABORATOR,"I agree that there is a lot of terminology that is somewhat similar and/or overlapping.
In math you have the basis of a vector space which when plotting in a coordinate system you sometimes call coordinates or axes.
Also you often use the phrase ""the x-coordinate of point p is ..."", So I understand why naming an axis ""coordinate"" might sound reasonable.
However in xarray (or numerics in general) you often deal with data that is not aligned to any axis in a given coordinate system.
Consider the following example: you have a time series of points that might be scattered randomly in your coordinate system. Now you can assign to each point a x and y coordinate.
In xarray you would call the dimension of the data e.g. ""time"". You will need two additional time series of data points for the x and y coordinates.
In xarray this would be something like that:
```python
da = xr.DataArray(
[5, 6, 7],
dims=""time"",
coords={
""x"": (""time"", [1, 2, 3]),
""y"": (""time"", [9, 8, 7]),
""time"": [0, 1, 2]
}
```
You can see that in this example we cannot easily define a x-y coordinate system since the data points are not on a grid. But still we can assign each data point a x and y coordinate.
Now finding a naming convention that fits both, random data points and lattices that are aligned with the coordinate system is not trivial.
That's why we choose to go with the following:
- **dimension**: name of an axis of a nd-array, this might be a ""real"" axis that has any real world equivalent or something as trivial as ""order in which the data has been aquisited"". In the example this was ""time"".
- **coordinate**: auxiliary data that can be used to identify the data values. In the example this was ""x"" and ""y"". (Basically it is a short name for ""coordinate variable"")
- **dimension coordinate**: a coordinate that assigns values to the dimension directly if possible. This is the case when the name of a coordinate is the same as a dimension. In the example this was ""time"" with the timestamps 0, 1 and 2 (probably this should be real timestamps).
Feel free to propose some changes to the documentation such that newcomers will find it easier to understand the terminology.","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,1707774178
https://github.com/pydata/xarray/pull/7840#issuecomment-1546029852,https://api.github.com/repos/pydata/xarray/issues/7840,1546029852,IC_kwDOAMm_X85cJosc,43316012,2023-05-12T16:57:53Z,2023-05-12T16:57:53Z,COLLABORATOR,Yes exactly. A dimension is only a name for an axis.,"{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,1707774178
https://github.com/pydata/xarray/pull/7840#issuecomment-1545930547,https://api.github.com/repos/pydata/xarray/issues/7840,1545930547,IC_kwDOAMm_X85cJQcz,43316012,2023-05-12T15:32:29Z,2023-05-12T15:32:29Z,COLLABORATOR,"This is a bit misleading. I think the term coordinate is correct, but you can be more precise and use dimension-coordinate, see:
https://docs.xarray.dev/en/stable/user-guide/data-structures.html#coordinates
Maybe we should start calling them index as well? But I think the concept of dimension-coordinates (when the coordinate has the same name as the dimension) is still relevant.","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,1707774178