Convert comma separated string to numeric columns
Old question, but I came across it from another recent question (which seems unrelated).
Both existing answers are appropriate, but I wanted to share an answer related to a package I have created called "splitstackshape" that is fast and has straightforward syntax.
Here's some sample data:
set.seed(1)
dat = data.frame(
reaction_time = apply(matrix(round(
runif(24, 1, 2000)), 6, 4), 1, paste, collapse = ","))
This is the splitting:
library(splitstackshape)
cSplit(dat, "reaction_time", ",")
# reaction_time_1 reaction_time_2 reaction_time_3 reaction_time_4
# 1: 532 1889 1374 761
# 2: 745 1322 769 1555
# 3: 1146 1259 1540 1869
# 4: 1817 125 996 425
# 5: 404 413 1436 1304
# 6: 1797 354 1984 252
And, optionally, if you need to take the rowMeans
:
rowMeans(cSplit(dat, "reaction_time", ","))
# [1] 1139.00 1097.75 1453.50 840.75 889.25 1096.75
I think you are looking for the strsplit() function;
a = "2000,1450,1800,2200"
strsplit(a, ",")
[[1]]
[1] "2000" "1450" "1800" "2200"
Notice that strsplit returns a list, in this case with only one element. This is because strsplit takes vectors as input. Therefore, you can also put a long vector of your single cell characters into the function and get back a splitted list of that vector. In a more relevant example this look like:
# Create some example data
dat = data.frame(reaction_time =
apply(matrix(round(runif(100, 1, 2000)),
25, 4), 1, paste, collapse = ","),
stringsAsFactors=FALSE)
splitdat = do.call("rbind", strsplit(dat$reaction_time, ","))
splitdat = data.frame(apply(splitdat, 2, as.numeric))
names(splitdat) = paste("trial", 1:4, sep = "")
head(splitdat)
trial1 trial2 trial3 trial4
1 597 1071 1430 997
2 614 322 1242 1140
3 1522 1679 51 1120
4 225 1988 1938 1068
5 621 623 1174 55
6 1918 1828 136 1816
and finally, to calculate the mean per person:
apply(splitdat, 1, mean)
[1] 1187.50 361.25 963.75 1017.00 916.25 1409.50 730.00 1310.75 1133.75
[10] 851.25 914.75 881.25 889.00 1014.75 676.75 850.50 805.00 1460.00
[19] 901.00 1443.50 507.25 691.50 1090.00 833.25 669.25
A nifty, if rather heavy-handed, way is to use read.csv
in conjunction with textConnection
. Assuming your data is in a data frame, df
:
x <- read.csv(textConnection(df[["reaction times"]]))