How to create a dataframe using a function based on user-input?

Question

I am trying to create a dataframe based on user-provided input. The user will decide the number of variables to be included in the dataframe.

Below I provide the codes that do what I am after. What I want to do is to create a function that does this same task.

var1 <- c(1:6)
var2 <- c(1:6)
var3 <- c(1:6)

var1 <- sample(var1, 10, replace = TRUE)
var2 <- sample(var2, 10, replace = TRUE)
var3 <- sample(var3, 10, replace = TRUE)

mydata <- data.frame(var1, var2, var3)

I expect the output below.

   var1 var2 var3
1     4    1    3
2     2    5    1
3     5    6    2
4     4    5    2
5     5    3    3
6     5    5    2
7     1    3    6
8     3    5    5
9     2    4    1
10    5    5    5

so the only parameter provided by the user is a single number? (or, if not, what parameters are provided by the user?) — IceCreamToucan
– IceCreamToucan, Commented Aug 15, 2019 at 20:30

IceCreamToucan · Accepted Answer · 2019-08-15 20:42:42Z

1

make_df <- function(n, x = 1:6, nrow = 10, var_prefix = 'var'){
  out <- as.data.frame(matrix(sample(x, nrow*n, TRUE), nrow, n))
  # or: out <- as.data.frame(replicate(n, sample(x, nrow, TRUE), simplify = F))
  setNames(out, paste0(var_prefix, seq_along(out)))
}


make_df(5)
#    var1 var2 var3 var4 var5
# 1     5    3    1    1    3
# 2     2    2    4    4    3
# 3     2    2    3    6    3
# 4     3    2    6    4    4
# 5     3    1    6    1    1
# 6     6    2    4    2    2
# 7     4    6    6    5    6
# 8     4    3    2    4    6
# 9     4    6    6    4    4
# 10    4    2    1    5    1

make_df(n = 5, x = 10:20, nrow = 4, var_prefix = 'col')
#   col1 col2 col3 col4 col5
# 1   16   13   16   10   11
# 2   17   10   12   12   16
# 3   16   11   10   11   15
# 4   15   14   13   14   11

edited Aug 15, 2019 at 20:42

answered Aug 15, 2019 at 20:32

IceCreamToucan

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1 Comment

user10904839 Over a year ago

Thanks. What if I want the user to also decide whether s/he wants to have 1:6, 1:10, 1:2 etc.?

Gregor Thomas · Accepted Answer · 2019-08-15 20:33:26Z

0

ncol = 3 # user input

nrow = 10 # your configuration
x = 1:6

# make the data frame
as.data.frame(matrix(sample(x, size = ncol * nrow, replace = TRUE), ncol = ncol))

answered Aug 15, 2019 at 20:33

Gregor Thomas

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