In R, how easy is it to combine many vectors into a data frame?
So, I know that I can use the data.frame command to combine multiple vectors into one dataframe, for example:
my.data <- data.frame(name1, age1, name20, age20, name38, age38)
(I know variable names don't make a lot of sense, why would I want name1, name20, and name38 in three different columns? Please ignore this: my actual variable names are different - this is just for illustration.)
The problem is that I have about 40 such vectors, and I have to combine many vectors in other parts of my code as well. Therefore, it would be convenient for me not to copy-paste a huge piece of code every time. So I thought about writing a for loop:
for (i in c("name", "age", "hgt"))
{
for (k in c(1,20,38))
{
my.data$i,as.character(k) <- data.frame(get(paste(i,as.character(k),sep="")))
}
}
But it doesn't work. Is it because I have to write "paste ()" around some of this code, or is it just a bad way to approach this problem? What is the correct way to loop through i and k and end up with a "newdata" framework with all the vectors as columns?
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Are you trying to achieve something like the following, perhaps?
name1 <- letters[1:10]
age1 <- 1:10
name20 <- letters[11:20]
age20 <- 11:20
name38 <- LETTERS[1:10]
age38 <- 21:30
paste.pattern <- paste(rep(c("name", "age"), times = 3),
rep(c(1, 20, 38), each = 2), sep = "")
newdata <- data.frame(sapply(paste.pattern, get))
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If all of your individual vectors have a similar structure (ex:) hgt
and number (ex:) 1
, then you can do something like this:
# test data
name1 <- letters[1:10]
age1 <- 1:10
name20 <- letters[11:20]
age20 <- 11:20
name38 <- LETTERS[1:10]
age38 <- 21:30
# group them up in a dataframe looking for "age" OR (|) "name" as the stem
data.frame(sapply(ls(pattern="^age[0-9]+$|^name[0-9]+$"),get))
# result:
age1 age20 age38 name1 name20 name38
1 1 11 21 a k A
2 2 12 22 b l B
3 3 13 23 c m C
4 4 14 24 d n D
5 5 15 25 e o E
6 6 16 26 f p F
7 7 17 27 g q G
8 8 18 28 h r H
9 9 19 29 i s I
10 10 20 30 j t J
This will restrict the included vectors to the stem / number naming pattern to make sure you don't get any surprises for your frame.
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