您在詢問"complete.obs"
和"pairwise.complete.obs"
之間的區別。
## example matrix
set.seed(0);X <- matrix(rnorm(10*3),ncol=3)
X[1:2,1] <- NA
X[3:4,2] <- NA
X[5:6,3] <- NA
# [,1] [,2] [,3]
# [1,] NA 0.7635935 -0.22426789
# [2,] NA -0.7990092 0.37739565
# [3,] 1.329799263 NA 0.13333636
# [4,] 1.272429321 NA 0.80418951
# [5,] 0.414641434 -0.2992151 NA
# [6,] -1.539950042 -0.4115108 NA
# [7,] -0.928567035 0.2522234 1.08576936
# [8,] -0.294720447 -0.8919211 -0.69095384
# [9,] -0.005767173 0.4356833 -1.28459935
#[10,] 2.404653389 -1.2375384 0.04672617
## complete
cor(X, use = "complete.obs")
# [,1] [,2] [,3]
#[1,] 1.00000000 -0.69629279 -0.09773585
#[2,] -0.69629279 1.00000000 -0.01228196
#[3,] -0.09773585 -0.01228196 1.00000000
## pairwise
cor(X, use = "pairwise.complete.obs")
# [,1] [,2] [,3]
#[1,] 1.00000000 -0.5531396 0.08229729
#[2,] -0.55313958 1.0000000 -0.10786401
#[3,] 0.08229729 -0.1078640 1.00000000
對於use = "complete.obs"
,與至少一個NA
任何行會被丟棄。因此,它本質上是做
X1 <- X[7:10, ] ## only the last 4 rows have no `NA`
cor(X1)
# [,1] [,2] [,3]
#[1,] 1.00000000 -0.69629279 -0.09773585
#[2,] -0.69629279 1.00000000 -0.01228196
#[3,] -0.09773585 -0.01228196 1.00000000
這裏,(1,2)
或(2,1)
進入-0.69629279
計算,只有4個數據。但是,如果您進行配對,則可以使用6個數據進行計算:
cor(X[5:10, 1], X[5:10, 2])
# [1] -0.5531396
歡迎來到SO。爲了幫助人們提供答案,通常需要將您的數據添加到問題中以製作可重複的示例。閱讀http://stackoverflow.com/questions/5963269/how-to-make-a-great-r-reproducible-example – dww