Sorting a dataframe by substring of columns values

Question

Been trying to find the answer to this question and haven't been able to. Say I have the dataframe,

DF <- data.frame (x=c("2,A","1,A","1,C", "1,B"), y = c(1,2,2,1))

yielding a Dataframe with two columns, the first of which has a number and a letter. How can I sort DF according to the number part of each of its rows? And then, add to it another column only with the letter. The objective is to obtain,

    x y z
1 1,A 2 A
2 2,A 1 A
3 1,B 1 B
4 1,C 2 C

Cheers

d.b · Accepted Answer · 2017-09-19 16:22:58Z

2

Use gsub to replace all digits or comma ("(\\d+|,)") and all non-digits ("\\D+") successively and then use order to sort DF based on that.

DF = DF[order(as.character(gsub("(\\d+|,)", "", DF$x)), as.numeric(gsub("\\D+", "", DF$x))),]
DF$z = gsub("(\\d+|,)", "", DF$x)
DF
#    x y z
#2 1,A 2 A
#1 2,A 1 A
#4 1,B 1 B
#3 1,C 2 C

edited Sep 19, 2017 at 16:22

answered Sep 19, 2017 at 16:16

d.b

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1 Comment

Arrebimbomalho Over a year ago

Fantastic. Thanks for the answer and the general tip on handling digits and strings! :)

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