r - 如何获取 p 值列表？

Question

我执行了 wilcox 测试，现在我想将 p.value 提取到列表或矩阵中。

DF <- data.frame(A1=sample(1:9, 10, T),
                     A2=sample(1:9, 10, T),
                     A3=sample(1:9, 10, T),
                     B1=sample(1:9, 10, T),
                     B2=sample(1:9, 10, T),
                     B3=sample(1:9, 10, T))


sampA <- DF[,grep('A', names(DF))]  # Sample with columns A
sampB <- DF[,grep('B', names(DF))]  # Sample with columns B


lapply(1:nrow(DF), function(i){
  wilcox.test(as.numeric(sampA[i,]), as.numeric(sampB[i,]), exact=FALSE )
}) 

我对每行进行 wilcox 测试的结果如下所示:我想知道如何获取列表或矩阵中的 p.value 并导出到 Excel 文件？ [[1]]

    Wilcoxon rank sum test with continuity correction

data:  as.numeric(sampA[i, ]) and as.numeric(sampB[i, ]) 
W = 3, p-value = 0.6579
alternative hypothesis: true location shift is not equal to 0 


[[2]]

    Wilcoxon rank sum test with continuity correction

data:  as.numeric(sampA[i, ]) and as.numeric(sampB[i, ]) 
W = 0, p-value = 0.0722
alternative hypothesis: true location shift is not equal to 0 


[[3]]

    Wilcoxon rank sum test with continuity correction

data:  as.numeric(sampA[i, ]) and as.numeric(sampB[i, ]) 
W = 6, p-value = 0.6579
alternative hypothesis: true location shift is not equal to 0 

Answer 1

只需添加 $p.value 即可从 wilcox.test 对象中提取 p.value :

lapply(1:nrow(DF), function(i){
  wilcox.test(as.numeric(sampA[i,]), as.numeric(sampB[i,]), exact=FALSE )$p.value
}) 

这给出:

[[1]]
[1] 1

[[2]]
[1] 1

[[3]]
[1] 0.8247781

[[4]]
[1] 0.8247781

通过使用 sapply 而不是 lapply，您将获得一个向量而不是列表，这可能更容易操作。

sapply(1:nrow(DF), function(i){
  wilcox.test(as.numeric(sampA[i,]), as.numeric(sampB[i,]), exact=FALSE )$p.value
}) 

# [1] 1.0000000 1.0000000 0.8247781 0.8247781 0.0765225 0.8247781 1.0000000
# [8] 0.8247781 0.2682859 0.0765225