Assigning strsplit results to multiple columns of a dataframe
I am trying to split a character vector into three different vectors inside a dataframe.
My details:
> df <- data.frame(filename = c("Author1 (2010) Title of paper",
"Author2 et al (2009) Title of paper",
"Author3 & Author4 (2004) Title of paper"),
stringsAsFactors = FALSE)
And I would like to share these 3 information ( authors
, year
, title
) on three different columns, so that it will be:
> df
filename author year title
1 Author1 (2010) Title1 Author1 2010 Title1
2 Author2 et al (2009) Title2 Author2 et al 2009 Title2
3 Author3 & Author4 (2004) Title3 Author3 & Author4 2004 Title3
I used strsplit
to split each filename
into a vector of 3 elements:
df$temp <- strsplit(df$filename, " \\(|\\) ")
But now I cannot find a way to put each item in a separate column. I can access certain information:
> df$temp[[2]][1]
[1] "Author2 et al"
but can't find how to put it in other columns
> df$author <- df$temp[[]][1]
Error
source to share
With the package tidyr
, here separate
:
separate(df, "filename", c("Author","Year","Title"), sep=" \\(|\\) "), remove=F)
# filename Author
# 1 Author1 (2010) Title of paper Author1
# 2 Author2 et al (2009) Title of paper Author2 et al
# 3 Author3 & Author4 (2004) Title of paper Author3 & Author4
# Year Title
# 1 2010 Title of paper
# 2 2009 Title of paper
# 3 2004 Title of paper
Leading and trailing spaces were considered
source to share
You can try tstrsplit
from devel versiondata.table
library(data.table)#v1.9.5+
setDT(df)[, c('author', 'year', 'title') :=tstrsplit(filename, ' \\(|\\) ')]
df
# filename author year
#1: Author1 (2010) Title of paper Author1 2010
#2: Author2 et al (2009) Title of paper Author2 et al 2009
#3: Author3 & Author4 (2004) Title of paper Author3 & Author4 2004
# title
#1: Title of paper
#2: Title of paper
#3: Title of paper
Edit: Included OP's section splitting pattern to remove spaces.
source to share
There is a basic t
-method (transpose) for data:
res <- t( data.frame( strsplit(df$filename, " \\(|\\) ") ))
colnames(res) <- c("author", "year", "title")
rownames(res) <- seq_along(rownames(res) )
res
#--------------
author year title
1 "Author1" "2010" "Title of paper"
2 "Author2 et al" "2009" "Title of paper"
3 "Author3 & Author4" "2004" "Title of paper"
source to share