Concatenate row-wise across specific columns of dataframe
I have a data frame with columns that, when concatenated (row-wise) as a string, would allow me to partition the data frame into a desired form.
> str(data)
'data.frame': 680420 obs. of 10 variables:
$ A : chr "2011-01-26" "2011-01-26" "2011-02-09" "2011-02-09" ...
$ B : chr "2011-01-26" "2011-01-27" "2011-02-09" "2011-02-10" ...
$ C : chr "2011-01-26" "2011-01-26" "2011-02-09" "2011-02-09" ...
$ D : chr "AAA" "AAA" "BCB" "CCC" ...
$ E : chr "A00001" "A00002" "B00002" "B00001" ...
$ F : int 9 9 37 37 37 37 191 191 191 191 ...
$ G : int NA NA NA NA NA NA NA NA NA NA ...
$ H : int 4 4 4 4 4 4 4 4 4 4 ...
For each row, I would like to concatenate the data in columns F, E, D, and C into a string (with the underscore character as separator). Below is my unsuccessful attempt at this:
data$id <- sapply(as.data.frame(cbind(data$F,data$E,data$D,data$C)), paste, sep="_")
And below is the undesired result:
> str(data)
'data.frame': 680420 obs. of 10 variables:
$ A : chr "2011-01-26" "2011-01-26" "2011-02-09" "2011-02-09" ...
$ B : chr "2011-01-26" "2011-01-27" "2011-02-09" "2011-02-10" ...
$ C : chr "2011-01-26" "2011-01-26" "2011-02-09" "2011-02-09" ...
$ D : chr "AAA" "AAA" "BCB" "CCC" ...
$ E : chr "A00001" "A00002" "B00002" "B00001" ...
$ F : int 9 9 37 37 37 37 191 191 191 191 ...
$ G : int NA NA NA NA NA NA NA NA NA NA ...
$ H : int 4 4 4 4 4 4 4 4 4 4 ...
$ 开发者_如何学Cid : chr [1:680420, 1:4] "9" "9" "37" "37" ...
..- attr(*, "dimnames")=List of 2
.. ..$ : NULL
.. ..$ : chr "V1" "V2" "V3" "V4"
Any help would be greatly appreciated.
Try
data$id <- paste(data$F, data$E, data$D, data$C, sep="_")
instead. The beauty of vectorized code is that you do not need row-by-row loops, or loop-equivalent *apply functions.
Edit Even better is
data <- within(data, id <- paste(F, E, D, C, sep=""))
Use unite
of tidyr
package:
require(tidyr)
data <- data %>% unite(id, F, E, D, C, sep = '_')
First parameter is the desired name, all next up to sep
- columns to concatenate.
Either stringr::str_c()
or paste()
will work.
require(stringr)
data <- within(data, str_c(F,E,D,C, sep="_")
or else
data <- within(data, paste(F,E,D,C, sep="_")
(stringr
is better performance on large datasets)
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