How to combine two vectors into a data frame - r

Question

I have two vectors like this
x <-c(1,2,3)
y <-c(100,200,300)
x_name <- "cond"
y_name <- "rating"
I'd like to output the dataframe like this:
> print(df)
cond rating
1 x 1
2 x 2
3 x 3
4 y 100
5 y 200
6 y 300
What's the way to do it?

Answer 1

While this does not answer the question asked, it answers a related question that many people have had:
x <-c(1,2,3)
y <-c(100,200,300)
x_name <- "cond"
y_name <- "rating"
df <- data.frame(x,y)
names(df) <- c(x_name,y_name)
print(df)
cond rating
1 1 100
2 2 200
3 3 300

Answer 2

x <-c(1,2,3)
y <-c(100,200,300)
x_name <- "cond"
y_name <- "rating"
require(reshape2)
df <- melt(data.frame(x,y))
colnames(df) <- c(x_name, y_name)
print(df)
UPDATE (2017-02-07):
As an answer to #cdaringe comment - there are multiple solutions possible, one of them is below.
library(dplyr)
library(magrittr)
x <- c(1, 2, 3)
y <- c(100, 200, 300)
z <- c(1, 2, 3, 4, 5)
x_name <- "cond"
y_name <- "rating"
# Helper function to create data.frame for the chunk of the data
prepare <- function(name, value, xname = x_name, yname = y_name) {
data_frame(rep(name, length(value)), value) %>%
set_colnames(c(xname, yname))
}
bind_rows(
prepare("x", x),
prepare("y", y),
prepare("z", z)
)

Answer 3

This should do the trick, to produce the data frame you asked for, using only base R:
df <- data.frame(cond=c(rep("x", times=length(x)),
rep("y", times=length(y))),
rating=c(x, y))
df
cond rating
1 x 1
2 x 2
3 x 3
4 y 100
5 y 200
6 y 300
However, from your initial description, I'd say that this is perhaps a more likely usecase:
df2 <- data.frame(x, y)
colnames(df2) <- c(x_name, y_name)
df2
cond rating
1 1 100
2 2 200
3 3 300
[edit: moved parentheses in example 1]

Answer 4

You can use expand.grid( ) function.
x <-c(1,2,3)
y <-c(100,200,300)
expand.grid(cond=x,rating=y)

Answer 5

Here's a simple function. It generates a data frame and automatically uses the names of the vectors as values for the first column.
myfunc <- function(a, b, names = NULL) {
setNames(data.frame(c(rep(deparse(substitute(a)), length(a)),
rep(deparse(substitute(b)), length(b))), c(a, b)), names)
}
An example:
x <-c(1,2,3)
y <-c(100,200,300)
x_name <- "cond"
y_name <- "rating"
myfunc(x, y, c(x_name, y_name))
cond rating
1 x 1
2 x 2
3 x 3
4 y 100
5 y 200
6 y 300

Answer 6

df = data.frame(cond=c(rep("x",3),rep("y",3)),rating=c(x,y))

Answer 7

Alt simplification of https://stackoverflow.com/users/1969435/gx1sptdtda above:
cond <-c(1,2,3)
rating <-c(100,200,300)
df <- data.frame(cond, rating)
df
cond rating
1 1 100
2 2 200
3 3 300