在每次迭代时打印 lapply 所以输出在列表元素之间

Question

似乎是一个基本问题。有没有办法在函数的迭代之间 print() 或 message() 以便打印位于控制台输出中的列表元素之间。示例：

two_sq <- function (x) {
  print(paste("this is ", x))
  x^2
}
lapply(1:3, two_sq)

给出：

    # [1] "this is  1"
    # [1] "this is  2"
    # [1] "this is  3"
    # [[1]]
    # [1] 1

    # [[2]]
    # [1] 4

    # [[3]]
    # [1] 9

期望输出：

# [1] "this is  1"

# # [[1]]
# # [1] 1

# [2] "this is  2"

# # [[2]]
# # [1] 4

# [3] "this is  3"

# # [[3]]
# # [1] 9

Answer 1

我们可以使用 for 循环

for(i in 1:3) two_sq(i)
#[1] "this is  1"
#[1] 1
#[1] "this is  2"
#[1] 4
#[1] "this is  3"
#[1] 9

哪里

two_sq <- function (x) {
    print(paste("this is ", x))
    print(x^2)
}

Answer 2

two_sq <- function (x) {
    print(paste("this is ", x))
    print(x^2)
}
invisible(lapply(1:3, two_sq))

# [1] "this is  1"
# [1] 1
# [1] "this is  2"
# [1] 4
# [1] "this is  3"
# [1] 9

在每次迭代时打印 lapply 所以输出在列表元素之间

print at each iteration lapply so output is between list elements

printing

message

r