I have the following dt:
| col1 | col2. |
|---|---|
| A | 1 |
| A | 2 |
| B | 3 |
What I want is :
| col1 | col2. |
|---|---|
| A | 1 |
| A | 1 |
| B | 2 |
I tried many things but it didn't work for me? Does anyone have an idea how to do it?
CodePudding user response：
We may use match
df1$col2 <- match(df1$col1, unique(df1$col1))