Having two dataframes:

```
x <- data.frame(numbers=c('1','2','3','4','5','6','7','8','9'), coincidence="NA")

```

and

```
y <- data.frame(numbers=c('1','3','10'))

```

How can I check if the observations in `y` (1, 3 and 10) also exist in `x` and fill accordingly the column `x["coincidence"]` (for example with YES|NO, TRUE|FALSE...).

I would do the same in Excel with a formula combining `IFERROR` and `VLOOKUP`, but I don't know how to do the same with R.

**Note:**
I am open to change data.frames to tables or use libraries. The dataframe with the numbers to check (`y`) will never have more than 10-20 observations, while the other one (`x`) will never have more than 1K observations. Therefore, I could also iterate with an `if`, if it´s necessary