[R] Filtering using multiple rows in dplyr

[Sumitrajit Dhar]

Hi Folks,

I have just started using dplyr and could use some help getting unstuck. It could well be that dplyr is not the package to be using, but let me just pose the question and seek your advice.

Here is my basic data frame.

head(h)
   subject ageGrp ear hearingGrp sex freq L2       Ldp     Phidp        NF       SNR
1 HALAF032      A   L          A   F    2  0 -23.54459  55.56005 -43.08282 19.538232
2 HALAF032      A   L          A   F    2  2 -32.64881  86.22040 -23.31558 -9.333224
3 HALAF032      A   L          A   F    2  4 -18.91058  42.12168 -35.60250 16.691919
4 HALAF032      A   L          A   F    2  6 -23.85937 297.94499 -20.70452 -3.154846
5 HALAF032      A   L          A   F    2  8 -14.45381 181.75329 -24.17094  9.717128
6 HALAF032      A   L          A   F    2 10 -20.42384  67.12998 -35.77357 15.349728

‘subject’ and ‘freq’ together make a set of data and I am interested in how the last four columns vary as a function of L2. So I grouped by ‘subject’ and ‘freq’ and can look at basic summaries.


h_byFunc <- h %>% group_by(subject, freq)

> h_byFunc %>% summarize(l = mean(Ldp), s = sd(Ldp) )

# A tibble: 1,175 x 4
# Groups:   subject [?]
   subject   freq       l     s
   <fct>    <int>   <dbl> <dbl>
 1 HALAF032     2 -13.8    8.39
 2 HALAF032     4 -15.8   11.0 
 3 HALAF032     8 -23.4    6.51
 4 HALAF033     2 -14.2    9.64
 5 HALAF033     4 -12.3    8.92
 6 HALAF033     8  -6.55  12.3 
 7 HALAF036     2 -14.9   12.6 
 8 HALAF036     4 -16.7   11.2 
 9 HALAF036     8 -21.7    6.56
10 HALAF039     2   0.242 12.4 
# ... with 1,165 more rows

What  I would like to do is filter some groups out based on various criteria. For example, if SNR > 3 in three consecutive L2 within a group, that group qualifies and I would add a column, say “clean” and assign it a value “Y.” Is there a way to do this in dplyr or should I be looking at a different way.

Thanks in advance for your help.

Regards,
Sumit