R 跨列滚动粘贴字符串

发布于04月26日

我有这类数据:

df <- data.frame(
  w1 = c("A", "B", "C", "E", "F", "G"),
  w2 = c("B", "G", "C", "D", "E", "V"),
  w3 = c("D", "S", "O", "F", NA, "N"),
  w4 = c("E", "U", NA, "T", NA, NA),
  w5 = c("C", NA, NA, NA, NA, NA)
)

我需要遍历column pairs，将单独的字符串滚动粘贴到bigram中.请注意，在实际数据中，字符串具有可变的字符长度和字符类型.

df[, paste0("bigr_", 1:4, "_", 2:5)] <- lapply(df[, 1:5], 
                                               function(x) paste(x[i], x[i+1], sep = " "))

expected output人是:

  w1 w2   w3   w4   w5 bigr_1_2 bigr_2_3 bigr_3_4 bigr_4_5
1  A  B    D    E    C      A B      B D      D E      E C
2  B  G    S    U <NA>      B G      G S      S U     <NA>
3  C  C    O <NA> <NA>      C C      C O     <NA>     <NA>
4  E  D    F    T <NA>      E D      D F      F T     <NA>
5  F  E <NA> <NA> <NA>      F E     <NA>     <NA>     <NA>
6  G  V    N <NA> <NA>      G V      V N     <NA>     <NA>

我最感兴趣的是dplyr种解决方案，但我对其他解决方案持开放态度，并表示感谢.

推荐答案

由于您对非dplyr解决方案持开放态度，我们可以在base R中修改您的原始代码:

df[, paste0("bigr_", 1:4, "_", 2:5)] <- mapply(paste, df[, 1:4], df[, 2:5])

# as NA is coerced to character, we need to find those positions and correct
x <- which(is.na(df[, 1:4]) | is.na(df[, 2:5]), arr.ind = TRUE)
x[, 2] <- x[, 2] + 5
df[x] <- NA
df

#   w1 w2   w3   w4   w5 bigr_1_2 bigr_2_3 bigr_3_4 bigr_4_5
# 1  A  B    D    E    C      A B      B D      D E      E C
# 2  B  G    S    U <NA>      B G      G S      S U     <NA>
# 3  C  C    O <NA> <NA>      C C      C O     <NA>     <NA>
# 4  E  D    F    T <NA>      E D      D F      F T     <NA>
# 5  F  E <NA> <NA> <NA>      F E     <NA>     <NA>     <NA>
# 6  G  V    N <NA> <NA>      G V      V N     <NA>     <NA>