R中具有列名称的矩阵堆叠

Question

I found many threads related to matrix stacking with column name but there is no information which help in this problem. I have a matrix like this

  Lcover County 8 9 53009 868.935 1171.0050 53055 NA 414.9733 53057 NA 276.5450 53073 706.700 NA 

and I am trying to create a dataframe like this

County Lcover Value  
53009   8     868.935  
53009   9    1171.0050   
53055   9     414.9733  
53057   9     276.5450  
53073   8     706.700

Would anyone suggest me, how can I do this?

Thanks in advance.

Deven

Answer 1

As Andrie noted, melt() function makes this trivially easy:

x <- read.table(text = "County        8         9   
  53009 868.935 1171.0050  
  53055      NA  414.9733  
  53057      NA  276.5450   
  53073 706.700        NA ", header = TRUE)

require(reshape2)
melt(x, id.vars = "County", na.rm=TRUE)

  County variable     value
1  53009       X8  868.9350
4  53073       X8  706.7000
5  53009       X9 1171.0050
6  53055       X9  414.9733
7  53057       X9  276.5450

The "X" appears in front of your columns because R tries to make valid column names with the make.names() function. You can disable that functionality with check.names = FALSE when reading in / creating your table. Or just drop the X from the resulting column with gsub("X","", variable) .If you want to retain the NA values in the melted data.frame, change na.rm = FALSE in the melt() function.