Question: Here is a reproducible example of my data. For the following data frame:

```
df <- data.frame(Subject = c('John', 'John', 'John', 'John','Mary', 'Mary', 'Mary', 'Mary'),
                 SNR = c(-4,-4,0,4,0,4,4,8))

```

I would like to add a column 'rank' that provides a ranking for SNR by Subject, so that it would look like this:

```
Subject   SNR   Rank
John      -4    1
John      -4    1
John       0    2
John       4    3
Mary       0    1
Mary       4    2
Mary       4    2
Mary       8    3

```

I have tried using:

```
dfNew <- transform(df, Rank = ave(SNR, Subject, FUN = function(x) rank(x, ties.method = "first")))

```

But I get the following:

```
Subject   SNR   Rank
John      -4    1
John      -4    2
John       0    3
John       4    4
Mary       0    1
Mary       4    2
Mary       4    3
Mary       8    4   

```

I have also tried using the different ties.method options, but none give me what I am looking for (i.e., ranking only from 1-3).

Any help would be much appreciated!

Answer: 
Using `aggregate` and `factor` in base R:

```
ag <- aggregate(SNR~Subject, df, function(x) as.numeric(factor(x)))
df$rank <- c(t(ag[,-1]))

  Subject SNR rank
1    John  -4    1
2    John  -4    1
3    John   0    2
4    John   4    3
5    Mary   0    1
6    Mary   4    2
7    Mary   4    2
8    Mary   8    3

```
```
library(dplyr)    
df %>%
     arrange(Subject, SNR) %>%
     group_by(Subject) %>%
     mutate(rank=dense_rank(SNR))

```

of course credit to @rich-scriven for mentioning `dense_rank()`