[R] How to change the order of columns in a data frame?

[Sarah Goslee]

Sorry, it should be:
> fakedata[, order(pos)]
  A X1 X2 X3 X4 X5 X6 X7 X8 X9
1 0  1  2  3  4  5  6  7  8  9
2 0  1  2  3  4  5  6  7  8  9
3 0  1  2  3  4  5  6  7  8  9

Using order also ensures that non-sequential column ids will work:

> fakedata <- data.frame(A=c(0,0,0), X1=c(1,1,1), X6=c(6,6,6), X7=c(7,7,7), X3=c(3,3,3), X4=c(4,4,4), X9=c(9,9,9), X2=c(2,2,2), X8=c(8,8,8))
> pos <- colnames(fakedata)[2:ncol(fakedata)]
> pos <- c(1, 1+as.numeric(gsub("X", "", pos)))
> fakedata
  A X1 X6 X7 X3 X4 X9 X2 X8
1 0  1  6  7  3  4  9  2  8
2 0  1  6  7  3  4  9  2  8
3 0  1  6  7  3  4  9  2  8
> fakedata[, order(pos)]
  A X1 X2 X3 X4 X6 X7 X8 X9
1 0  1  2  3  4  6  7  8  9
2 0  1  2  3  4  6  7  8  9
3 0  1  2  3  4  6  7  8  9

Sarah

2012/2/17 Joel Fürstenberg-Hägg <joelf at life.ku.dk>:
> It does not work when using more variables, and my data frames usually
> contains about thousand columns...
>
> Best,
>
> Joel
>
>> fakedata <- data.frame(A=c(0,0,0), X1=c(1,1,1), X6=c(6,6,6), X7=c(7,7,7),
>> X3=c(3,3,3), X4=c(4,4,4), X9=c(9,9,9), X2=c(2,2,2), X8=c(8,8,8),
>> X5=c(5,5,5))
>> fakedata
>   A X1 X6 X7 X3 X4 X9 X2 X8 X5
> 1 0  1  6  7  3  4  9  2  8  5
> 2 0  1  6  7  3  4  9  2  8  5
> 3 0  1  6  7  3  4  9  2  8  5
>> pos <- colnames(fakedata)[2:ncol(fakedata)]
>> pos
> [1] "X1" "X6" "X7" "X3" "X4" "X9" "X2" "X8" "X5"
>> pos <- c(1, 1+as.numeric(gsub("X", "", pos)))
>> pos
>  [1]  1  2  7  8  4  5 10  3  9  6
>> fakedata[,  pos]
>   A X1 X9 X2 X7 X3 X5 X6 X8 X4
> 1 0  1  9  2  7  3  5  6  8  4
> 2 0  1  9  2  7  3  5  6  8  4
> 3 0  1  9  2  7  3  5  6  8  4
>
>>>> Sarah Goslee <sarah.goslee at gmail.com> 17-02-2012 14:36 >>>
>> fakedata <- data.frame(A=c(0,0,0), X2=c(2,2,2), X1=c(1,1,1), X3=c(3,3,3))
>> fakedata
>   A X2 X1 X3
> 1 0  2  1  3
> 2 0  2  1  3
> 3 0  2  1  3
>> pos <- colnames(fakedata)[2:ncol(fakedata)]
>> pos <- c(1, 1+as.numeric(gsub("X", "", pos)))
>> fakedata[,  pos]
>   A X1 X2 X3
> 1 0  1  2  3
> 2 0  1  2  3
> 3 0  1  2  3
>>
>
> Sarah
>
> 2012/2/17 Joel Fürstenberg-Hägg <joelf at life.ku.dk>:
>
>> Dear all,
>>
>> I have a data frame in which the columns need to be ordered. The first
>> column X is at the right position, but the remaining columns X1-Xn should be
>> ordered like this: X1, X2, X3 etc instead of like below.
>>
>>> colnames(pos1)
>>  [1] "X"   "X1"  "X10" "X11" "X12" "X13" "X14" "X15" "X16" "X17" "X18"
>> "X19" "X2"  "X20" "X3"  "X4"  "X5"  "X6"  "X7"  "X8"  "X9"
>>
>>> pos1[1:5,1:5]
>>      X       X1       X10       X11       X12
>> 1 100.5 7949.469 18509.064  8484.969 17401.056
>> 2 101.5 3080.058  7794.691  3211.323  8211.058
>> 3 102.5 1854.347  4347.571  1783.846  4827.338
>> 4 103.5 2064.441  8421.746  2012.536  8363.785
>> 5 104.5 9650.402 26637.926 10730.647 27053.421
>>
>> I am trying to first change the first column name to something without an
>> X and save as a vector. I would then remove the X from each position use the
>> vector for renaming the columns. Then the column 2-n could be ordered, I
>> hope...
>>
>> colnames(pos)[1] <- "Mass"
>> columnNames <- colnames(pos)
>>
>> Does any of you have an idea how to do this, or perhaps there is a
>> smoother solution?
>> Would it be easier to solve it if the contents of the first column were
>> extracted and used as row names instead?
>>
>> Best regards,
>>
>> Joel
>>
>
>
> --
> Sarah Goslee
> http://www.functionaldiversity.org



-- 
Sarah Goslee
http://www.stringpage.com
http://www.sarahgoslee.com
http://www.functionaldiversity.org