Selecting rows on basis of the string length of two columns

Question

I want to select the rows of a data frame in which the length of the string in the column v3 is equal to the length of the string of the column v4. My dataframe 'df' looks like: ``` v1 v2 v3 v4 1 456 . C T 2 462 . C T 3 497 . C T 4 499 . GC AC 5 499 . GC G 6 499 . GC CC 7 513 . GCACA GCA 8 513 . GCACA GCACACA 9 513 . GCACA ACACA 10 513 . GCACA GCACACACA 11 513 . GCACA GCACACACACA 12 513 . GCACA GACCACA 13 513 . GCACA G 14 521 . ACN A 15 522 . CNN C ``` The output should be: ``` v1 v2 v3 v4 1 456 . C T 2 462 . C T 3 497 . C T 4 499 . GC AC 9 513 . GCACA ACACA ``` I have tried: `new_df = df[nchar(str_sub(df$v3))==nchar(str_sub(df$v4))]`

Accepted Answer

@agstudy got the most important part. I would add that `str_sub` (from the `stringr` package I assume) is not doing anything useful here. Last, you could use `subset` to avoid the repetitive use of `df$`. So you can do:

```
df[nchar(df$v3) == nchar(df$v4), ]
```

or

```
subset(df, nchar(v3) == nchar(v4))
```

Selecting rows on basis of the string length of two columns

Solution

Problem