Hi,

I have got following columns' names:

```
"P18" "P18" "P19" "P19" "P20" "P20" "P21" "P21" "P22" "P22" "P23" "P23"
```

I would like to rename these columns by adding to first column "correlation" and to the second "p-value", in order to my columns'names look like this"

P18_correlation, P18_p_value and so on. How do I do it, please ?