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Guys I'm new to this language ,I'm running cluster analysis on a data frame but when I calculate the distance I get this warning "NAs introduced by coercion". What does this mean?

d <- dist(as.matrix(mydata1))

  Warning message:
In dist(as.matrix(mydata1)) : NAs introduced by coercion

My data sample is 

Metafamily     Total         July cpc      July cse_pla    July offline   July organic  
xerox 8560     275.829417    0.20943223    0.032628862     0.169210813    0.1130048 
office-supplie  246.9125664  0.057833047   0.020209909     0.535358617    0.136165617

In this apart from Metafamily column all columns are numeric in class.

Guys please help me out from this issue.

4

1 回答 1

15

这是造成问题的第一列：

> a <- c("1", "2",letters[1:5], "3")
> as.numeric(a)
[1]  1  2 NA NA NA NA NA  3
Warning message:
NAs introduced by coercion

里面dist必须有一个对数字的强制，它会生成上面的 NA。

我建议在dist没有第一列的情况下申请，或者如果可能的话最好将其移到rownames，因为结果会有所不同：

> dist(df)
          1         2         3         4
2 1.8842186                              
3 1.9262360 1.2856110                    
4 3.2137871 1.7322788 2.9838920          
5 1.3299455 0.9872963 1.9158079 1.8889050
Warning message:
In dist(df) : NAs introduced by coercion
> dist(df[-1])
         1        2        3        4
2 1.538458                           
3 1.572765 1.049697                  
4 2.624046 1.414400 2.436338         
5 1.085896 0.806124 1.564251 1.542284

as.matrix顺便说一句：调用时不需要dist。无论如何它都会在内部这样做。

编辑：使用行名

rownames(df) <- df$id

> df
  id       var1       var2
A  A -0.6264538 -0.8204684
B  B  0.1836433  0.4874291
C  C -0.8356286  0.7383247
D  D  1.5952808  0.5757814
E  E  0.3295078 -0.3053884

> dist(df[-1]) # you colud also remove the 1st col at all, using df$id <- NULL.
         A        B        C        D
B 1.538458                           
C 1.572765 1.049697                  
D 2.624046 1.414400 2.436338         
E 1.085896 0.806124 1.564251 1.542284
于 2013-10-08T10:47:25.950 回答