r - 计算字符串中的单个数字

Question

我有一串串联的整数:

A = "883745"

我想对单个数字进行计算。我在这里提取每个数字:

N1 = as.numeric(substr(A , 1, 1))
N2 = as.numeric(substr(A , 2, 2))
N3 = as.numeric(substr(A , 3, 3))
N4 = as.numeric(substr(A , 4, 4))
N5 = as.numeric(substr(A , 5, 5))
N6 = as.numeric(substr(A , 6, 6))

然后我需要计算:

N1 *  nchar(A)    + 
N2 * (nchar(A) - 1) + 
N3 * (nchar(A) - 2) + 
N4 * (nchar(A) - 3) + 
N5 * (nchar(A) - 4) + 
N6 * (nchar(A) - 5)

如何在循环中执行此操作？

Answer 1

substring 而不是 substr 对于这些向量化子字符串操作很有用:

nc <- seq(nchar(A))
sum(as.numeric(substring(A, nc, nc)) * rev(nc))
#[1] 134