How to fill in every nth row with values from another column with dplyr?-CodePudding

Hi supposed I have a dataframe as such

temp <- data.frame(value = sample(c ( 1:312), 20 ), value2 = sample(c ( 1:312), 20 )  )

   value value2
1    217    270
2    299    155
3     77    249
4    116     89
5     54     18
6    248    228
7    154    273
8    218    146
9    149    131
10   134     68
11   282     47
12   169    196
13    20    276
14   233    240
15   222     92
16   102      1
17   297     49
18     9     65
19   289    118
20    75    255

What I like to do is fill in every 3rd row with the data from value2. So for example, all rows above rows 1 & 2 would be 0 and the third row would 249, rows 5 &6 are 0 and row 7 would be 273 and so fourth.

Would be great if I can do with dplyr. thanks in advance.

CodePudding user response：

You may use if_else -

set.seed(123)
temp <- data.frame(value = sample(c(1:312), 20), value2 = sample(c(1:312), 20))

temp %>%
  mutate(value3 = if_else(row_number() %% 3 == 0, value2, 0L))

#   value value2 value3
#1    179    211      0
#2     14     78      0
#3    195     81     81
#4    306     43      0
#5    118    143      0
#6    299     32     32
#7    229    109      0
#8    244    263      0
#9    311     23     23
#10   153    135      0
#11    90    224      0
#12    91    166    166
#13   256    217      0
#14   197    290      0
#15   301     69     69
#16   137     72      0
#17    26     76      0
#18     7     63     63
#19   297    141      0
#20   254    210      0