如何創建一個基於空行作爲分隔符在R列的列

Question

我想創建一個基於另一空列作爲分隔符的列，這裏是我的表。

 
     TABLE1  TABLE2 
V1 V2 INDEX  V1 
U 30 1  30 
V 3 2  54 
V 25 3  61 
V 4 4   6 
      5   . 
U 54 6   . 
V 9 7   . 
V 22 8   
V 90 9   
     10   
U 61 11 
.  . . 
.  . . 

現在我試圖讓這樣的事情，

 
     TABLE1 
V1 V2 INDEX MATCH   
U 30 1 30   
V 3 2 30   
V 25 3 30   
V 4 4 30   
      5   
U 54 6 54  
V 9 7 54  
V 22 8 54  
V 90 9 54  
     10   
U 61 11 61 
.  . .  61 
.  . .  . 

我想使用DIST（rbind（））找到的指標之間的距離V1 [I] = U以及索引中的空行將給我使用apply（）或for循環創建MATCH列的次數。

Answer 1

下面是使用data.table結合一種可能的方法與zoo

library(data.table) ; library(zoo) # loading the packages 
setkey(setDT(TABLE1), V2) # converting to `data.table` object and setting a key for a binary join 
TABLE1[TABLE2, MATCH := i.V1] # conducting binary join (I'm assuming the column in TABLE2 called "V1") and updating MATCH by reference 
setorder(TABLE1, INDEX, na.last = TRUE) # reordering back by INDEX 
TABLE1[, MATCH := na.locf(MATCH)] # filling the NAs with the previous value in MATCH 
#  V1 V2 INDEX MATCH 
# 1: U 30  1 30 
# 2: V 3  2 30 
# 3: V 25  3 30 
# 4: V 4  4 30 
# 5: NA  5 30 
# 6: U 54  6 54 
# 7: V 9  7 54 
# 8: V 22  8 54 
# 9: V 90  9 54 
# 10: NA 10 54 
# 11: U 61 11 61 

---

DATA

TABLE1 <- structure(list(V1 = structure(c(2L, 3L, 3L, 3L, 1L, 2L, 3L, 3L, 
3L, 1L, 2L), .Label = c("", "U", "V"), class = "factor"), V2 = c(30L, 
3L, 25L, 4L, NA, 54L, 9L, 22L, 90L, NA, 61L), INDEX = 1:11), .Names = c("V1", 
"V2", "INDEX"), class = "data.frame", row.names = c(NA, -11L)) 

TABLE2 <- structure(list(V1 = c(30L, 54L, 61L, 6L)), .Names = "V1", class = "data.frame", row.names = c(NA, 
-4L))