I have a bunch of charter strings of various lengths that contain numbers and letters. All charter strings end with an `_` followed with a number (e.g. \_30, \_100, \_500, or \_1000).

The `String` object below contains a few examples. 

```
Strings <- c("DET37_30", "DET37_500",  "Ele_100",  "Ele_1000", "NDVI_MeanMax_100", "RadWint_30", "RadWint_500", "Slope_100")

```

For each column name, I want to select all the numbers, letters, and `_` prior to the final `_number`

For example `DET37_30` and `DET_500` would result in `DET37`, and `Ele_100` and `Ele_1000` would result in Ele.

In other words, I want all values before the ending `_30`, `_100`, `_500`, or `_1000`.