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R: concatenate the values ​​of the components of a list with another list specifying which ones go together

I have two lists. lst1

contains symbolic vectors that represent variable names:

lst1 <- list(c("var1", "var2"),
             "item1",
             c("var12", "var15", "var17"),
             c("item3", "item5", "item7"),
             "var22",
             c("var27", "var29", "var33", "var34"))

As you can see, some components lst1

contain one or more variable names. lst2

contains values ​​for each variable name in lst1

, but each in a separate component:

lst2 <- list(var1 = as.character(c(1, 2, 3, 5, 6)),
             var2 = as.character(c(1, 3, 4, 5, 6, 7)),
             item1 = letters[1:5],
             var12 = as.character(1:3),
             var15 = as.character(1:5),
             var17 = as.character(1:6),
             item3 = letters[3:8],
             item5 = letters[4:9],
             item7 = letters[5:10],
             var22 = as.character(2:7),
             var27 = as.character(4:10),
             var29 = as.character(3:8),
             var33 = as.character(1:4),
             var34 = as.character(4:9))

These two lists are much larger and are a product of previous code that I have dealt with. I would like to get a list like lst1

, where instead of variable names, each component contains its concatenated elements from lst2

for all names that belong to that component in lst1

, something like

lst3 <- list(c("1", "2", "3", "5", "6", "1", "3", "4", "5", "6", "7"),
             c("a", "b", "c", "d", "e"),
             c("1", "2", "3", "1", "2", "3", "4", "5", "1", "2", "3", "4", "5", "6"),
             c("c", "d", "e", "f", "g", "h", "d", "e", "f", "g", "h", "i", "e", "f", "g", "h", "i", "j"),
             c("2", "3", "4", "5", "6", "7"),
             c("4", "5", "6", "7", "8", "9", "10", "3", "4", "5", "6", "7", "8", "1", "2", "3", "4", "4", "5", "6", "7", "8", "9"))

and maybe get only sorted unique values ​​in each component. How can I do that?

EDIT: I updated the post in the section where I provide an example for lst3

, because I noticed bugs in lst3

.

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1 answer


Try

lapply(lst1, function(x) sort(unique(unlist(lst2[x], use.names=FALSE))))


If we don't need sort

and get the valuesunique 

lapply(lst1, function(x) unlist(lst2[x], use.names=FALSE))
#[[1]]
#[1] "1" "2" "3" "5" "6" "1" "3" "4" "5" "6" "7"

#[[2]]
#[1] "a" "b" "c" "d" "e"

#[[3]]
#[1] "1" "2" "3" "1" "2" "3" "4" "5" "1" "2" "3" "4" "5" "6"

#[[4]]
#[1] "c" "d" "e" "f" "g" "h" "d" "e" "f" "g" "h" "i" "e" "f" "g" "h" "i" "j"

#[[5]]
#[1] "2" "3" "4" "5" "6" "7"

#[[6]]
#[1] "4"  "5"  "6"  "7"  "8"  "9"  "10" "3"  "4"  "5"  "6"  "7"  "8"  "1"  "2" 
#[16] "3"  "4"  "4"  "5"  "6"  "7"  "8"  "9"
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