Sorting columns of a data frame by column name

Question

This may be a simple question, but I don't know how to sort the columns alphabetically.

test = data.frame(C = c(0, 2, 4, 7, 8), A = c(4, 2, 4, 7, 8), B = c(1, 3, 8, 3, 2)) # CAB # 1 0 4 1 # 2 2 2 3 # 3 4 4 8 # 4 7 7 3 # 5 8 8 2 

I like to order columns by column names in alphabetical order to achieve

 # ABC # 1 4 1 0 # 2 2 3 2 # 3 4 8 4 # 4 7 3 7 # 5 8 2 8 

For others, I want my own specific order:

 # BAC # 1 4 1 0 # 2 2 3 2 # 3 4 8 4 # 4 7 3 7 # 5 8 2 8 

Please note that my datasets are huge, with 10,000 variables. Therefore, the process should be more automated.

Answer 1

You can use order in names and use this to arrange columns with a subset:

 test[ , order(names(test))] ABC 1 4 1 0 2 2 3 2 3 4 8 4 4 7 3 7 5 8 2 8 

For your own specific order, you will need to define your own name mapping for the order. It will depend on how you would like to do this, but replacing any function with the one with order above should give the desired result.

You can, for example, see Order lines of a data frame in accordance with the target vector, which sets the desired order , i.e. you can match your names data frame against the target vector containing the desired column order.

Answer 2

 test = data.frame(C=c(0,2,4, 7, 8), A=c(4,2,4, 7, 8), B=c(1, 3, 8,3,2)) 

Using the following simple replacement function can be performed (but only if there are not many columns in the data frame):

 test <- test[, c("A", "B", "C")] 

For others:

 test <- test[, c("B", "A", "C")] 

Answer 3

Here is dplyr obligatory answer in case someone wants to do this with a handset.

 test %>% select(sort(names(.))) 

Answer 4

  test[,sort(names(test))] 

sorting by column names can easily work.

Answer 5

If you need only one or several columns in front and you don’t care about the order of the rest:

 require(dplyr) test %>% select(B, everything()) 

Answer 6

Here is what I found to achieve a similar problem with my dataset.

First, do what I mentioned above, for example,

 test[ , order(names(test))] 

Secondly, use the all () function in dplyr to move certain columns of interest (for example, "D", "G", "K") at the beginning of the data frame, placing the alphabetically ordered columns after these,

 select(test, D, G, K, everything()) 

Answer 7

Similar to the other syntax above, but for training - can you sort by column names?

 sort(colnames(test[1:ncol(test)] )) 

Answer 8

Another option is to use str_sort() from the stringr library with argument numeric = TRUE

str_sort(c("V3", "V1", "V10"), numeric = TRUE)

# [1] V1 V3 V11

Answer 9

So that a specific column appears first, and then alphabetically, I would suggest the following solution:

 test[, c("myFirstColumn", sort(setdiff(names(test), "myFirstColumn")))]