Question

我正在尝试对不同的数据帧进行相关性测试，这些数据帧表示分配给员工的唯一商店的数量，并且各列同时悔改不同的区域。我的数据框按每个员工拥有的唯一存储的数量进行划分：
unique_store_breakdown <- split(Data, as.factor(Data$unique_stores))

理想情况下，我想要输出：

Region -- unique_store -- correlation    
Midwest ------- 1 --------------  .05  
Midwest ------- 2 --------------  .04  
.  
.  
Southeast ----- 1 -------------  0.75  
.  
.

cor_tests <-list() 
counter = 0 

for (i in unique(j$region)){
for (j in 1: length(unique_store_breakdown)){
  counter = counter + 1
  #Create new variables for correlation test
  x = as.numeric(j[j$region == i,]$quality)
  y = as.numeric(j[j$region == i,]$rsv)

  cor_tests[[counter]] <- cor.test(x,y)
}}
cor_tests

我能够一次对一个数据帧运行此命令，但是当我尝试添加嵌套循环（j项）时，出现错误“错误：$运算符对原子向量无效。此外，我还想将结果作为数据框而不是列表输出。

Answer 1

如果您要做的只是为每个商店执行cor.test()，则使用by()应该非常简单。 by()的输出是一个常规列表，只是打印有些特殊。

# example data
set.seed(1)
dtf <- data.frame(store=rep(1:3, each=30), rsv=rnorm(90))
dtf$quality <- dtf$rsv + rnorm(90, 0, dtf$store)

# perform cor.test for every store
by(dtf, dtf$store, function(x) cor.test(x$quality, x$rsv))
# dtf$store: 1
# 
#   Pearson's product-moment correlation
# 
# data:  x$quality and x$rsv
# t = 5.5485, df = 28, p-value = 6.208e-06
# alternative hypothesis: true correlation is not equal to 0
# 95 percent confidence interval:
#  0.4915547 0.8597796
# sample estimates:
#       cor 
# 0.7236681 
# 
# ------------------------------------------------------------------------------
# dtf$store: 2
# 
#   Pearson's product-moment correlation
# 
# data:  x$quality and x$rsv
# t = 0.68014, df = 28, p-value = 0.502
# alternative hypothesis: true correlation is not equal to 0
# 95 percent confidence interval:
#  -0.2439893  0.4663368
# sample estimates:
#       cor 
# 0.1274862 
# 
# ------------------------------------------------------------------------------
# dtf$store: 3
# 
#   Pearson's product-moment correlation
# 
# data:  x$quality and x$rsv
# t = 2.2899, df = 28, p-value = 0.02977
# alternative hypothesis: true correlation is not equal to 0
# 95 percent confidence interval:
#  0.04304952 0.66261810
# sample estimates:
#      cor 
# 0.397159 
#

如何使用嵌套循环运行cor.test

1 个答案: