CODEWITHSUNDEEP
r
Jeff Bradshaw
Jeff Bradshaw

Reputation: 23

How do I simply generate a numbered list from a data frame?

I am trying to construct a code chunk that, after inputting data from an Excel sheet, constructs a data frame of "refereed publications" from within the past five years (the initial data are filtered through a couple of subset commands on lines 1 and 2). I've pasted some of the code below that I think helps explain what I'm trying to do and how I am trying to do it.

The third line pubsfive <- within(pubsfive, rwnum <- 1) is to initialize a new column within the pubsfive data frame. Lastly, I'm trying to run a for loop in an attempt to number each line by its row name (1 through 10, in this case). I don't exactly know what I'm doing with the for loop, but I'm trying to code for each row in the new column called, rwnum that simply outputs the row number. I should be able to concatenate all of the columns and then pass the object to kable to then print a nice 5-year publications list.

This probably isn't the most eloquent code, so I am open to any clarifying questions or tips. 

pubsfive <- subset(pubs, pubs$Contribution == "Refereed Publications")
pubsfive<- subset(pubsfive, pubsfive$year >= 2014, select = c(Authors, year, Title))
pubsfive <- within(pubsfive, rwnum <- 1)
pubsfive <- for (i in 1:nrow(pubsfive))
  {within(pubsfive, rwnum <- rownames(pubsfive)[i])}

Upvotes: 2

Views: 59

Answers (1)

Ben Bolker
Ben Bolker

Reputation: 226162

I'm not sure what's wrong with this:

pubsfive <- subset(pubs,
     Contribution == "Refereed Publications" & year > 2014,
     select = c(Authors, year, Title))
pubsfive$rwnum <- rownames(pubsfive)

The first line is a slightly more compact way of doing your first two lines, the third assigns a vector to the new column rwnum ... if you want the row numbers first you might prefer

pubsfive <- data.frame(rwname=rownames(pubsfive),
                       pubsfive)

It's not clear to me whether you want the row names or seq(nrow(pubsfive)) ...

Upvotes: 1

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