R cannot melt data.frame

Question

I have the following data.frame, called tableMS:

     X   Y        Z        T
1  375 855 455.7259 3777.856
2  395 969 347.8306   2506.7
3  449 811 309.9512 5         


        

Answer 1

I had this same problem, but the cause was different. I got the same error message "names do not match previous names", but it was due to using the package dplyr.

Turns out, it is a known issue with dplyr. According to the GitHub issue, it will occur on some version of dplyr and reshape but not on others.

The output from dplyr is not just a data.frame - it inherits from data.frame. So after using dplyr to produce data this is the result:

class(data)

> [1] "tbl_df"     "tbl"        "data.frame"

melt(data, id = c("X", Y"))

>Error in match.names(clabs, names(xi)) : 
names do not match previous names

To fix this issue, I had to convert the dplyr output to a data frame. This also appears to be the recommended way to combine these packages:

data <- as.data.frame(data)
class(data)

> [1] "data.frame"

melt(data, id = c("X", "Y"))

The last block then completes without error.