将 dataframe 数组列拆分为多个二进制列 [R]

Question

Array column is current and the others are the goal

I have a column of arrays and I would like to split it out into multiple binaries. I have created all the columns by using

dat[,unique(unlist(df$array_column))] = 0

I tried to use an ifelse statement to then set the columns to '1' as needed however using %in% does not work with ifelse . I could create a nested for loop however I have millions of rows and am looking for a faster solution than that.

testdf = data.frame('a'=c(1,2,3,4,5),'array_column'=c('a-b-c','b-a','c-d','d-e-e','e-a'),stringsAsFactors = F)
testdf$array_column = strsplit(testdf$array_column,'-')

Answer 1

I think the question is rather how convert a list of vectors into a binary matrix/data.frame

Here is a solution

testdf = data.frame('a'=c(1,2,3,4,5),'array_column'=c('a-b-c','b-a','c-d','d-e-e','e-a'),stringsAsFactors = F)                     
testdf$array_column = strsplit(testdf$array_column,'-')    

library('plyr')                                                                                                

# Creates a list of data.frames with 1s for each value observed                                                                   
binary <- lapply(testdf$array_column, function(x) {                                                                                                                                                   
                     vals <- unique(x) 
                     x <- setNames(rep(1,length(vals)), vals);                                                                      
                     do.call(data.frame, as.list(x))                                                                                
                })                                                                                                                  

# Joins into single data.frame                                                                                                                
result <- do.call(rbind.fill, binary)                                                                                                
result[is.na(result)] <- 0                                                                                                          

result                                                                                                                              
#   a b c d e                                                                                                                       
# 1 1 1 1 0 0                                                                                                                       
# 2 1 1 0 0 0                                                                                                                       
# 3 0 0 1 1 0                                                                                                                       
# 4 0 0 0 1 1                                                                                                                       
# 5 1 0 0 0 1