sorting rows according to a row pattern

Question

I want to re-arrange the rows of a dataframe that looks like this:

qs=c("q11", "q22", "q2", "q6", "q10")
ans=rep(1,times=length(qs))
df=data.frame(qs,ans)
arrange(df,qs)

 qs ans
1 q10   1
2 q11   1
3  q2   1
4 q22   1
5  q6   1

However, I want the sorting of the rows to look in the much more logical order, such as this:

 qs ans
1  q2   1
2  q6   1
3 q10   1
4 q11   1
5 q22   1

Can someone help me with this ?

Answer 1

Use R base:

df <- df[order(as.integer(gsub("q", "", as.character(df$qs)))), ]

For you example df, this gives:

   qs ans
3  q2   1
4  q6   1
5 q10   1
1 q11   1
2 q22   1

You might note that rownames are not 1, 2, 3, 4, 5 after reordering; you can do:

rownames(df) <- 1:nrow(df)

to make it look nice:

   qs ans
1  q2   1
2  q6   1
3 q10   1
4 q11   1
5 q22   1