我想在管道处理中使用 dplyr::mutate 而不是 plyr::ddply 函数

Question

我想通过 mutate 函数而不是 ddplyr one 来做我在这里所做的事情。是否有可能在这里以某种方式执行非矢量化操作？

test <- tibble::tibble(
  x = c(1,2,3),
  y = c(0.5,1,1.5)
)
d <- c(1.23, 0.99, 2.18)

test %>% mutate(., s = (function(x, y) {
  dn <- dnorm(x = d, mean = x, sd = y)
  s <- sum(dn)
  s
})(x,y))

test %>% plyr::ddply(., c("x","y"), .fun = function(row) {
  dn <- dnorm(x = d, mean = row$x, sd = row$y)
  s <- sum(dn)
  s
})

Answer 1

一种流行的方法是使用dplyr 函数：rowwise()。

library(tidyverse)

test <- tibble::tibble(
  x = c(1,2,3),
  y = c(0.5,1,1.5)
)
d <- c(1.23, 0.99, 2.18)

test %>% 
  rowwise() %>%                                # prior to mutate specify calculate rowwise
  mutate(., s = (function(x, y) {
    dn <- dnorm(x = d, mean = x, sd = y)
    s <- sum(dn)
    s})(x,y))

这会产生以下结果：

# A tibble: 3 x 3
      x     y     s
  <dbl> <dbl> <dbl>
1     1   0.5 1.56 
2     2   1   0.929
3     3   1.5 0.470