[R] How to reshape wide format data.frame to long format?

[Abhijit Dasgupta]

As for your second question, you could certainly do

newcodesM = transform(newcodesM, variable1 = unlist(strsplit(variable,'\\.'))[1], variable2 = unlist(strsplit(variable, '\\.'))[2], variable3 = unlist(strsplit(variable,'\\.'))[3])

though I'm sure there is a more efficient use of strsplit in this context. 

Abhijit
On Jan 20, 2011, at 10:51 AM, Fredrik Karlsson wrote:

> Dear list,
> 
> I need to convert this data.frame
> 
>> names(codesM)
> [1] "key"        "AMR.pa1.M"  "AMR.pa2.M"  "AMR.pa3.M"  "AMR.pa4.M"
> [6] "AMR.pa5.M"  "AMR.pa6.M"  "AMR.pa7.M"  "AMR.pa8.M"  "AMR.pa9.M"
> [11] "AMR.pa10.M" "AMR.ta1.M"  "AMR.ta2.M"  "AMR.ta3.M"  "AMR.ta4.M"
> [16] "AMR.ta5.M"  "AMR.ta6.M"  "AMR.ta7.M"  "AMR.ta8.M"  "AMR.ta9.M"
> [21] "AMR.ta10.M" "AMR.ka1.M"  "AMR.ka2.M"  "AMR.ka3.M"  "AMR.ka4.M"
> [26] "AMR.ka5.M"  "AMR.ka6.M"  "AMR.ka7.M"  "AMR.ka8.M"  "AMR.ka9.M"
> [31] "AMR.ka10.M" "SMR.pa1.M"  "SMR.pa2.M"  "SMR.pa3.M"  "SMR.pa4.M"
> [36] "SMR.pa5.M"  "SMR.pa6.M"  "SMR.pa7.M"  "SMR.pa8.M"  "SMR.pa9.M"
> [41] "SMR.pa10.M" "SMR.ta1.M"  "SMR.ta2.M"  "SMR.ta3.M"  "SMR.ta4.M"
> [46] "SMR.ta5.M"  "SMR.ta6.M"  "SMR.ta7.M"  "SMR.ta8.M"  "SMR.ta9.M"
> [51] "SMR.ta10.M" "SMR.ka1.M"  "SMR.ka2.M"  "SMR.ka3.M"  "SMR.ka4.M"
> [56] "SMR.ka5.M"  "SMR.ka6.M"  "SMR.ka7.M"  "SMR.ka8.M"  "SMR.ka9.M"
> [61] "SMR.ka10.M"
>> dim(codesM)
> [1] 42 61
> 
> into a 3 x  2501 data.frame where the "key" variable is kept, the
> values in columns 2-61 above is inserted into a "values" column and
> the name of the column is inserted in a third column ("variable"
> perhaps).
> 
> Like
> 
> key                         variable              value
> POSTOFF_1_1    AMR.pa1.M       5
> POSTOFF_1_1    AMR.pa2.M       3
> ....
> 
> I think I should be able to do this using the "reshape" function, but
> I cannot get it to work. I think I need some help to understand
> this...
> 
> 
> (If I could split the "variable" into three separate columns splitting
> by ".", that would be even better.)
> 
> I appreciate all the help I could get.
> 
> /Fredrik
> 
> -- 
> "Life is like a trumpet - if you don't put anything into it, you don't
> get anything out of it."
> 
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