Extracting unique strings from a factor variable
I have a variable that contains the names of the actors.
(actor=structure(c(4L, 1L, 6L, 2L, 5L, 3L), .Label = c("Christian Bale, Tom Hardy, Anne Hathaway, Gary Oldman",
"Jamie Foxx, Christoph Waltz, Leonardo DiCaprio, Kerry Washington",
"Jennifer Lawrence, Josh Hutcherson, Liam Hemsworth, Stanley Tucci",
"Leonardo DiCaprio, Joseph Gordon-Levitt, Ellen Page, Ken Watanabe",
"Leonardo DiCaprio, Mark Ruffalo, Ben Kingsley, Max von Sydow",
"Robert Downey Jr., Chris Evans, Scarlett Johansson, Jeremy Renner"
), class = "factor"))
# [1] Leonardo DiCaprio, Joseph Gordon-Levitt, Ellen Page, Ken Watanabe
# [2] Christian Bale, Tom Hardy, Anne Hathaway, Gary Oldman
# [3] Robert Downey Jr., Chris Evans, Scarlett Johansson, Jeremy Renner
# [4] Jamie Foxx, Christoph Waltz, Leonardo DiCaprio, Kerry Washington
# [5] Leonardo DiCaprio, Mark Ruffalo, Ben Kingsley, Max von Sydow
# [6] Jennifer Lawrence, Josh Hutcherson, Liam Hemsworth, Stanley Tucci
# 6 Levels: Christian Bale, Tom Hardy, Anne Hathaway, Gary Oldman ...
I want to extract all the actors' names (first name + last name) from it and make them columns in the output matrix.
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If you want to extract the unique names of the members, you can get the specified members using a function as.character
, split it into commas with strsplit
, concatenate all vectors in the resulting list with unlist
, and capture the unique names with unique
:
(all.actors <- unique(unlist(strsplit(as.character(actor), ", "))))
# [1] "Leonardo DiCaprio" "Joseph Gordon-Levitt" "Ellen Page" "Ken Watanabe"
# [5] "Christian Bale" "Tom Hardy" "Anne Hathaway" "Gary Oldman"
# [9] "Robert Downey Jr." "Chris Evans" "Scarlett Johansson" "Jeremy Renner"
# [13] "Jamie Foxx" "Christoph Waltz" "Kerry Washington" "Mark Ruffalo"
# [17] "Ben Kingsley" "Max von Sydow" "Jennifer Lawrence" "Josh Hutcherson"
# [21] "Liam Hemsworth" "Stanley Tucci"
By using as.character(actor)
, this code uses only those subjects that are displayed in the factor actor
, even if this factor has many more unused levels. If you use levels(actor)
instead, you get all the contributors at the factor level, regardless of whether they are used in actors
. You can use whichever you prefer when defining all.actors
.
If you wanted a matrix indicating the inclusion of each actor in each element actor
, you could do
mat <- sapply(strsplit(as.character(actor), ", "), function(x) all.actors %in% x)
row.names(mat) <- all.actors
mat
# [,1] [,2] [,3] [,4] [,5] [,6]
# Leonardo DiCaprio TRUE FALSE FALSE TRUE TRUE FALSE
# Joseph Gordon-Levitt TRUE FALSE FALSE FALSE FALSE FALSE
# Ellen Page TRUE FALSE FALSE FALSE FALSE FALSE
# Ken Watanabe TRUE FALSE FALSE FALSE FALSE FALSE
# Christian Bale FALSE TRUE FALSE FALSE FALSE FALSE
# Tom Hardy FALSE TRUE FALSE FALSE FALSE FALSE
# Anne Hathaway FALSE TRUE FALSE FALSE FALSE FALSE
# Gary Oldman FALSE TRUE FALSE FALSE FALSE FALSE
# Robert Downey Jr. FALSE FALSE TRUE FALSE FALSE FALSE
# Chris Evans FALSE FALSE TRUE FALSE FALSE FALSE
# Scarlett Johansson FALSE FALSE TRUE FALSE FALSE FALSE
# Jeremy Renner FALSE FALSE TRUE FALSE FALSE FALSE
# Jamie Foxx FALSE FALSE FALSE TRUE FALSE FALSE
# Christoph Waltz FALSE FALSE FALSE TRUE FALSE FALSE
# Kerry Washington FALSE FALSE FALSE TRUE FALSE FALSE
# Mark Ruffalo FALSE FALSE FALSE FALSE TRUE FALSE
# Ben Kingsley FALSE FALSE FALSE FALSE TRUE FALSE
# Max von Sydow FALSE FALSE FALSE FALSE TRUE FALSE
# Jennifer Lawrence FALSE FALSE FALSE FALSE FALSE TRUE
# Josh Hutcherson FALSE FALSE FALSE FALSE FALSE TRUE
# Liam Hemsworth FALSE FALSE FALSE FALSE FALSE TRUE
# Stanley Tucci FALSE FALSE FALSE FALSE FALSE TRUE
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