Is there a way to extract rows based on condition of one column?

Question

I wish to extract all columns for rows 4, 11 and so on. If you look at my posted data, my wish is to extract row values that are present immediately before an 'A' in column 'xsampa'. For example, all the columns for row 4 (that occur before row 5 that contains an 'A' in column 'xsampa'). I can manually extract them but anything better will definitely save me some labour.

Many thanks if you help me out.

Filename Speaker Consonant      tdiff xsampa
1  AK_baagge.TextGrid       1  Geminate 0.23165381      B
2  AK_baagge.TextGrid       1  Geminate 0.09607762      b
3  AK_baagge.TextGrid       1  Geminate 0.15799431     A:
4  AK_baagge.TextGrid       1  Geminate 0.08753738     g:
5  AK_baagge.TextGrid       1  Geminate 0.02668823      A
6  AK_baagge.TextGrid       1  Geminate 0.12917102     e:
7  AK_baagge.TextGrid       1  Geminate 0.87323879      E
8   AK_baagi.TextGrid       1 Singleton 0.22415281      B
9   AK_baagi.TextGrid       1 Singleton 0.11448148      b
10  AK_baagi.TextGrid       1 Singleton 0.15873483     A:
11  AK_baagi.TextGrid       1 Singleton 0.09716495      g
12  AK_baagi.TextGrid       1 Singleton 0.05387364      A
13  AK_baagi.TextGrid       1 Singleton 0.10125358     i:
14  AK_baagi.TextGrid       1 Singleton 0.70685099      E
15   AK_baga.TextGrid       1 Singleton 0.78044616      B
16   AK_baga.TextGrid       1 Singleton 0.09659531      b
17   AK_baga.TextGrid       1 Singleton 0.09220461      @
18   AK_baga.TextGrid       1 Singleton 0.05159068      g
19   AK_baga.TextGrid       1 Singleton 0.13482446     A:
20   AK_baga.TextGrid       1 Singleton 0.46999388      E

@JonSpring Thanks again! I understand, 'lag' here is extracting the rows before an 'A:'. My output should be the rows that are preceded by an 'A' and not an 'A:'. When I try replacing 'A:' with an 'A', the lag () outputs unwanted rows. Perhaps, lead () function? — Pranav_b, Feb 20 '21 at 04:13
If you have already got your answer instead of editing the question to include the answer you can put the answer in the answer section below which might help future visitors. You can answer your own questions. — Ronak Shah, Feb 20 '21 at 05:11
Aha, thanks for the clarification @Pranav_b. I didn't read closely enough and only noticed the preceding "A:" and not the following "A." By all means you should add your answer, glad you found it. — Jon Spring, Feb 20 '21 at 17:28
@RonakShah haha, never knew we could post our own answer. Thanks. — Pranav_b, Feb 21 '21 at 04:37

score 1 · Accepted Answer · edited Feb 21 '21 at 19:10

As @Jon Spring replied in the comments, the answer to this question is to use dplyr:: lead() function instead of lag(). This way, all the rows in the column 'xsampa' that contained the value 'A' will be filtered and produce the desired output.

The lag() function will simply produce rows one behind the input.

ANSWER:

mydata_new<- mydata %>% filter(lead (xsampa) == "A")

Output:

Filename Speaker Consonant      tdiff xsampa
1    AK_baagge.TextGrid       1  Geminate 0.08753738     g:
2     AK_baagi.TextGrid       1 Singleton 0.09716495      g
3     AK_bagga.TextGrid       1  Geminate 0.11573271     g:
4     AK_buute.TextGrid       1 Singleton 0.08538239     t`
5    AK_buutte.TextGrid       1  Geminate 0.21568940    t`:  
6   AK_chaakki.TextGrid       1  Geminate 0.12341936     k:
7     AK_chape.TextGrid       1 Singleton 0.06812137      p
8    AK_chappe.TextGrid       1  Geminate 0.14723284     p:
9      AK_fati.TextGrid       1 Singleton 0.06677743     t`
10    AK_fatti.TextGrid       1  Geminate 0.13503550    t`:
11     AK_gada.TextGrid       1 Singleton 0.06472276    d_d
12    AK_gadda.TextGrid       1  Geminate 0.13475387   d_d:
13   AK_jaaddi.TextGrid       1  Geminate 0.12847036   d_d:
14    AK_jaadi.TextGrid       1 Singleton 0.06732941    d_d
15    AK_katha.TextGrid       1 Singleton 0.01338915  t_d_h
16     AK_kute.TextGrid       1 Singleton 0.04600485    t_d
17    AK_kutte.TextGrid       1  Geminate 0.15318115   t_d:
18  AK_raajegi.TextGrid       1 Singleton 0.03868537     dZ
19 AK_raajjegi.TextGrid       1  Geminate 0.10578673    dZ:
20     AK_sada.TextGrid       1 Singleton 0.05504982    d_d

Is there a way to extract rows based on condition of one column?

1 Answers1