即使使用na.rm = T，素食NA值也会破坏envfit。示例图片在帖子中

Question

我正在尝试将envfit箭头叠加到像这样的NMDS图表上（当我用假数字替换缺失值时）：

但是，根据我们的实际数据，它不会给出箭头，而是单独标记每个点，如下所示：

任何建议都将不胜感激。

Code:
# Make MDS
x.mds <- metaMDS(x_matrix, trace = FALSE)
# Extract point co-ordinates for putting into ggplot
NMDS <- data.frame(MDS1 = x.mds$points[,1], MDS2 = x.mds$points[,2])

p <- ggplot(NMDS, aes(MDS1, MDS2))
p + geom_point()

#environmental variables
ef <- envfit(x.mds ~ pH + Ammonia + DO, x.env)
ef <- envfit(x.mds ~ pH + Ammonia + DO, x.env, na.rm = TRUE)    ##ALTERNATIVE
plot(ef)

数据：

Sample  Region  pH  Ammonia Nitrate BOD DO
15  N   7.618   0.042   0.845   1   NA  
34  N   7.911   0.04    7.41    8   5.62    
42  SE  7.75    NA  3.82    1   21.629  
........


> ef

***VECTORS

           NMDS1    NMDS2     r2 Pr(>r)
pH       0.50849 -0.86107 0.0565  0.719
Ammonia  0.99050 -0.13751 0.0998  0.504
DO      -0.88859 -0.45871 0.1640  0.319
P values based on 999 permutations.

1 observation deleted due to missingness

> str(ef)
List of 3
 $ vectors  :List of 4
  ..$ arrows      : num [1:3, 1:2] 0.508 0.991 -0.889 -0.861 -0.138 ...
  .. ..- attr(*, "dimnames")=List of 2
  .. .. ..$ : chr [1:3] "pH" "Ammonia" "DO"
  .. .. ..$ : chr [1:2] "NMDS1" "NMDS2"
  .. ..- attr(*, "decostand")= chr "normalize"
  ..$ r           : Named num [1:3] 0.0565 0.0998 0.164
  .. ..- attr(*, "names")= chr [1:3] "pH" "Ammonia" "DO"
  ..$ permutations: num 999
  ..$ pvals       : num [1:3] 0.719 0.504 0.319
  ..- attr(*, "class")= chr "vectorfit"
 $ factors  : NULL
 $ na.action:Class 'omit'  int 17
 - attr(*, "class")= chr "envfit"