R/dplyr: How do I initialize an empty list of data frames?

You can bypass this problem by using a list instead of a vector, as lists do not have a fixed size.
output_list = list()

for(ii in 1:10){
# make this iteration df
df = data.frame(random = runif(10))

# store in list
output_list[[ii]] = df
}

Also works for c(‘a’,’b’,’c’) instead of 1:10 in the for loop.