将向量从循环保存到列表或数据中

Question

I have to generate several iterations of some mathematical operations, which result in a vector of length 100 each time.

I want to store each vector of n iterations into a list or data.frame, after running a for loop.

Basically, save my results (vector of length 100) into a list to be converted into a matrix or directly into a matrix.

For instance:

for (i in 1:10){
     r <- rnorm(100,0,1)
     }

In each of the 10 iterations, r generates a vector of length 100. The final desired output is a data.frame with 100 rows and 10 columns, each column representing each of the generated iterations.

How to build such matrix or data.frame?

Many thanks

Answer 1

We can use replicate

replicate(10, rnorm(100))

If needed we can convert it into a dataframe (showing a smaller example for n = 5 )

set.seed(1234)
as.data.frame(replicate(10, rnorm(5)))

#       V1      V2       V3      V4      V5       V6      V7      V8      V9     V10
#1 -1.2071  0.5061 -0.47719 -0.1103  0.1341 -1.44820  1.1023 -1.1676  1.4495 -0.9685
#2  0.2774 -0.5747 -0.99839 -0.5110 -0.4907  0.57476 -0.4756 -2.1800 -1.0686 -1.1073
#3  1.0844 -0.5466 -0.77625 -0.9112 -0.4405 -1.02366 -0.7094 -1.3410 -0.8554 -1.2520
#4 -2.3457 -0.5645  0.06446 -0.8372  0.4596 -0.01514 -0.5013 -0.2943 -0.2806 -0.5238
#5  0.4291 -0.8900  0.95949  2.4158 -0.6937 -0.93595 -1.6291 -0.4659 -0.9943 -0.4968

Answer 2

Using a for loop you can do

# choose number of columns you need
ncolumns <- 10
# generate an "empty" matrix
m <- matrix(NA, 100, ncolumns)
# run for loop
for (i in 1:ncolumns){
  m[ , i] <- rnorm(100,0,1)
}