在 R 中删除数据框中的相邻重复项

Question

这是我在 Stack Overflow 上的第一个问题。我在 R 中有一个数据框，其中有一百多个列应该有重复项。我不能使用 unique()，因为我只想删除每列中与行相邻的重复项。

L = list(c("AL", "AL", "AI", "AH", "BK", "CD", "CE", "BT", "BP", 
"BD", "BI", "AL"), c("AL", "AL", "AI", "AH", "BK", "AU", "BK", 
"CD", "V", "CE", "CE"), c("AL", "AL", "AI", "AH", "AU", "BK", 
"BQ"))
do.call(cbind, lapply(L, `length<-`, max(lengths(L))))

song 1  song 2  song 3
AL  AL  AL
AL  AL  AL
AI  AI  AI
AH  AH  AH
BK  BK  AU
CD  AU  BK
CE  BK  BQ
BT  CD  
BP  V   
BD  CE  
BI  CE  
AL      



song 1  song 2  song 3
AL  AL  AL
AI  AI  AI
AH  AH  AH
BK  BK  AU
CD  AU  BK
CE  BK  BQ
BT  CD  
BP  V   
BD  CE  
BI      
AL

我看到以前的答案似乎对单个列来说工作得很好。

解决方案是

df = df[with(df, c(x[-1]!= x[-nrow(df)], TRUE)),]

我见过 rle 解决方案，但它们不起作用。考虑到我的数据框中的列长度不同，我想知道是否有一种方法可以遍历所有列。

Answer 1

假设您有一个这样的列表：

songs
# $song_1
# [1] "AL" "AL" "AI" "AH" "BK" "CD" "CE" "BT" "BP" "BD" "BI" "AL"
# 
# $song_2
# [1] "AL" "AL" "AI" "AH" "BK" "AU" "BK" "CD" "V"  "CE" "CE"
# 
# $song_3
# [1] "AL" "AL" "AI" "AH" "AU" "BK" "BQ"

与 dput 可重复共享：

songs = structure(list(song_1 = c("AL", "AL", "AI", "AH", "BK", "CD", 
"CE", "BT", "BP", "BD", "BI", "AL"), song_2 = c("AL", "AL", "AI", 
"AH", "BK", "AU", "BK", "CD", "V", "CE", "CE"), song_3 = c("AL", 
"AL", "AI", "AH", "AU", "BK", "BQ")), .Names = c("song_1", "song_2", 
"song_3"))

您可以对单个列表项中的相邻元素进行重复数据删除，类似于您在问题中使用的数据框方法。

with(songs, song_1[song_1[-1] != song_1[-length(song_1)]])
# [1] "AL" "AI" "AH" "BK" "CD" "CE" "BT" "BP" "BD" "BI"

要对列表中的所有项目执行此操作，我们使用 lapply 和匿名函数：

lapply(songs, function(s) s[s[-1] != s[-length(s)]])
# $song_1
# [1] "AL" "AI" "AH" "BK" "CD" "CE" "BT" "BP" "BD" "BI"
# 
# $song_2
# [1] "AL" "AI" "AH" "BK" "AU" "BK" "CD" "V" 
# 
# $song_3
# [1] "AL" "AI" "AH" "AU" "BK"

当然，您可以将 lapply 的结果分配给新对象以覆盖现有对象。

请注意，由于您发布数据的方式，您的数据需要相当多的工作才能进入 R。下次请使用dput()或分享代码创建模拟数据。

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