r - 为按因子分组的每个回归提取 R^2(R 平方)值

Question

我想知道是否有办法为每个回归方程提取 R2。

d <- data.frame(
  state = rep(c('NY', 'CA'), 10),
  year = rep(1:10, 2),
  response= rnorm(20)
)

library(plyr)
models <- dlply(d, "state", function(df) 
  lm(response ~ year, data = df))

ldply(models, coef)
l_ply(models, summary, .print = TRUE)

我试过

l_ply(models, summary$r.squared, .print = TRUE)

但这会引发以下错误消息

Error in summary$r.squared : object of type 'closure' is not subsettable

Answer 1

您可以这样做以获得 R 平方值和系数:

ldply(models, function(x) {r.sq <- summary(x)$r.squared
                           intercept <- summary(x)$coefficients[1]
                           beta <- summary(x)$coefficients[2]
                           data.frame(r.sq, intercept, beta)})
#  state        r.sq intercept        beta
#1    CA 0.230696121 0.4915617 -0.12343947
#2    NY 0.003506936 0.1971734 -0.01227367