在R中的数据框中搜索特定字符集

Question

I have created a set of characters with some missing values like this

bp <- rep(NA, 5)
bp[c(2,4)] <- c("sugar","milk")
bp

> bp
[1] NA  "sugar" NA  "milk" NA 

I'm looking for a way to use bp for searching a larger data frame in order to find similar occurances of bp (and where), but with NAs filled.

For example,

[1] any1  "sugar" any2  "milk" any3 
[2] any2  "sugar" any5  "milk" any1 
[3] any6  "sugar" any1  "milk" any3 
[4] any8  "sugar" any7  "milk" any6
[5] any1  "sugar" any2  "milk" any3 

EDIT: A part of the data frame looks something like this

c("milk", "sugar", "sugar", "creme", "carw", "milk", "creme", "carw", 
"sugar", "carw", "creme", "sugar", "sugar", "milk", "milk", "creme", 
"sugar", "sugar", "carw", "carw", "carw", "milk", "sugar", "sugar", 
"carw", "sugar", "milk", "sugar", "creme", "carw", "carw", "carw", 
"creme", "carw", "carw", "creme", "creme", "milk", "carw", "milk", 
"milk", "creme", "creme", "creme", "milk", "milk", "creme", "carw", 
"carw", "milk", "milk", "creme", "creme", "carw", "carw", "milk", 
"sugar", "carw", "milk", "carw", "creme", "sugar", "sugar", "creme", 
"sugar", "sugar", "creme", "sugar", "carw", "sugar", "carw", 
"carw", "creme", "sugar", "milk", "milk", "carw", "carw", "milk", 
"creme", "sugar", "carw", "milk", "sugar", "sugar", "milk", "sugar", 
"creme", "milk", "milk", "carw", "milk", "sugar", "carw", "sugar", 
"carw", "creme", "creme", "carw", "milk", "milk", "milk", "milk", 
"carw", "carw", "milk", "milk", "carw", "sugar", "milk", "milk", 
"milk", "creme", "carw", "creme", "milk", "milk", "milk", "creme", 
"carw", "milk", "carw", "carw", "carw", "carw", "carw", "carw"
)

I would normaly use this for searching the entire data frame, but in this situation it's tricky.

library(data.table)

n1 <- length(bp)
bp.pos <- setDT(data.frame)[,  which(Reduce(`&`, Map(`==`, shift(value1, seq(n1)-1, 
                                                                             type = "lead"), 
                                                                 bp)))]

Any help would be appreciated.

Answer 1

Here's an attempt based I what I understand of your problem. I call the vector you shared x :

test = sapply(seq_along(bp), function(i) bp[i] == x[(0 + i):(length(x) - length(bp) + i)])
test = test | is.na(test)
res = which(apply(test, 1, all))
res = lapply(res, function(x) x + seq_along(bp) - 1)
final = lapply(res, function(z) x[z])
names(final) = lapply(res, "[", 1)

# $`11`
# [1] "creme" "sugar" "sugar" "milk"  "milk" 
# 
# $`12`
# [1] "sugar" "sugar" "milk"  "milk"  "creme"
# 
# $`56`
# [1] "milk"  "sugar" "carw"  "milk"  "carw" 
# 
# $`73`
# [1] "creme" "sugar" "milk"  "milk"  "carw" 
# 
# $`80`
# [1] "creme" "sugar" "carw"  "milk"  "sugar"
# 
# $`83`
# [1] "milk"  "sugar" "sugar" "milk"  "sugar"
# 
# $`86`
# [1] "milk"  "sugar" "creme" "milk"  "milk" 
# 
# $`108`
# [1] "carw"  "sugar" "milk"  "milk"  "milk" 

The result is a named list where the name is the starting index of x and the value is the matched vector. This gives you both the "where" as well as the match in one object.