【问题标题】:Correlation matrix by group按组的相关矩阵
【发布时间】:2014-07-20 22:48:31
【问题描述】:

这是我的数据框

df <- structure(list(g1 = structure(c(1L, 1L, 1L, 1L, 1L, 2L, 2L, 2L, 2L, 2L), .Label = c("A", "C"), class = "factor"), g2 = structure(c(1L, 1L, 1L, 2L, 2L, 1L, 1L, 2L, 2L, 2L), .Label = c("a", "b"), class = "factor"), v1 = 1:10, v2 = c(5, 5, 6, 2, 4, 4, 2, 1, 9, 8), v3 = c(29, 10, 56, 93, 20, 14, 12, 87, 67, 37)), .Names = c("g1", "g2",  "v1", "v2", "v3"), row.names = c(NA, -10L), class = "data.frame")

   g1 g2 v1 v2 v3
1   A  a  1  5 29
2   A  a  2  5 10
3   A  a  3  6 56
4   A  b  4  2 93
5   A  b  5  4 20
6   C  a  6  4 14
7   C  a  7  2 12
8   C  b  8  1 87
9   C  b  9  9 67
10  C  b 10  8 37

我想为组 g1 和 g2 的每个组合(在本例中为 Aa、Ab、Ca、Cb)创建一个 v1、v2 和 v3 的相关矩阵。所以我想使用包 Hmisc 并与 plyr 结合使用

library(Hmisc)
library(plyr)

这可行(当然忽略组):

rcorr(as.matrix(df[,3:5]), type="pearson")

但这不是:

cor.matrix <- dlply(df, .(g1,g2), rcorr(as.matrix(df[,3:5]), type="pearson"))
Error:attempt to apply non-function

我做错了什么?

【问题讨论】:

  • 这个怎么样? by(df, INDICES = list(df$g1, df$g2), FUN = function(x) cor(x[, c("v1", "v2", "v3")]))
  • 这很好用,不过,谢谢,我想使用 Hmisc 的 rcorr 的原因是它还生成了一个带有 p 值的矩阵。我认为cor 不可能做到这一点?

标签: r plyr correlation hmisc


【解决方案1】:

如果您每组有超过 4 个观察值,则此方法有效(因此,为什么我 rbinded 您的 df 加上另外 2 个 df):

df <- structure(list(g1 = structure(c(1L, 1L, 1L, 1L, 1L, 2L, 2L, 2L, 2L, 2L), 
    .Label = c("A", "C"), class = "factor"), 
    g2 = structure(c(1L, 1L, 1L, 2L, 2L, 1L, 1L, 2L, 2L, 2L), 
    .Label = c("a", "b"), class = "factor"), 
    v1 = 1:10, v2 = c(5, 5, 6, 2, 4, 4, 2, 1, 9, 8), 
    v3 = c(29, 10, 56, 93, 20, 14, 12, 87, 67, 37)), 
    .Names = c("g1", "g2",  "v1", "v2", "v3"), row.names = c(NA, -10L), 
    class = "data.frame")


df <- rbind(df, df, df)

library(Hmisc)
lapply(split(df, df[, 1:2]), function(x) {
    rcorr(as.matrix(x[,3:5]), type="pearson")
})

编辑这行得通:

dlply(df, .(g1,g2), function(x) rcorr(as.matrix(x[,3:5]), type="pearson"))

【讨论】:

  • 完美,谢谢!不过,你有解释为什么dlply 不起作用吗?只是好奇;)
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