CODEWITHSUNDEEP
rsortingdataframe
bdevil
bdevil

Reputation: 185

Ordering columns in data frame

I have a data frame with the following column names:

well, DIV10SD7, DIV11SD7, DIV7SD7, DIV9SD7

However, I want the order to be the following: 

well, DIV7SD7, DIV9SD7, DIV10SD7, DIV11SD7

So basically, I want to sort by the number after "DIV" and before "SD7". Additionally, I want to leave out the "well" column when I sort.

When I use the following command: 

df[,order(names(df))]

The order of the data frame is unchanged, with the exception of the well column, which moves to the end. I believe this is because R reads each string one character at a time. So, in this case, all the numbers that begin with 1 (e.g. DIV10 and DIV11) are placed before DIV7 and DIV9.

Is there a way to change this behavior?

Upvotes: 2

Views: 281

Answers (1)

A5C1D2H2I1M1N2O1R2T1
A5C1D2H2I1M1N2O1R2T1

Reputation: 193667

You can try the mixedorder function from the "gtools" package:

mydf[c(1, mixedorder(names(mydf)[-1]) + 1)]
##   well DIV7SD7 DIV9SD7 DIV10SD7 DIV11SD7
## 1    1       7       9        3        5
## 2    2       8      10        4        6

Sample data:

mydf <- structure(list(well = 1:2, DIV10SD7 = 3:4, DIV11SD7 = 5:6, DIV7SD7 = 7:8, 
        DIV9SD7 = 9:10), .Names = c("well", "DIV10SD7", "DIV11SD7", 
    "DIV7SD7", "DIV9SD7"), row.names = 1:2, class = "data.frame")

I'd also suggest converting your dataset to a data.table so that you can make use of the set functions in "data.table" (like setcolorder). This will let you update the column order by reference.

Upvotes: 4

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