Dynamically set colnames from character string in flextable

Question

The flextable help details describes adding new headers as manually typing each existing header name against each new header name, like this:

library(flextable)
ft_1 <- regulartable(head(iris))
ft_1 <- set_header_labels(ft_1, Sepal.Length = "SL",
                          Sepal.Width = "SW", Petal.Length = "PL",
                          Petal.Width = "PW"
)
ft_1

How can I just add all new header names from a character string such as

(names2<-c('SL','SW','PL','PW','SPECIES'))
[1] "SL"      "SW"      "PL"      "PW"      "SPECIES"

?

So far I have managed a very hacky solution:

names(names2)<-names(ft_1$header$dataset[1,])

ft_1$header$dataset[1,]<-names2

Karolyn

What about changing the colnames in the dataset before converting it to a flextable? – Rash

@user10626943 thanks for the comment. This is to add a second header, in addition to the colnames of the dataframe. – Karolyn

Hopefully @davidgohel sees this and responds with something good. He's usually pretty responsive an helpful :) But I've always had trouble getting ft to work as I think it should :P – Rash

@user10626943 yes I noticed he is very helpful whilst searching through old SO questions on ft. – Karolyn

:) yes, I am receiving alerts when tags officer/flextable are used and I am trying to answer when I can. – Murky

Answer 1

set_header_labels is made for minor modifications of header values. You can use set_header_df if you want to map df column names with a set of one or more new header rows: https://davidgohel.github.io/flextable/articles/layout.html#define-headers-with-a-reference-table

library(flextable)

names1 <- c("Sepal.Length", "Sepal.Width", "Petal.Length", "Petal.Width", "Species")
names2 <- c('SL','SW','PL','PW','SPECIES')

ft <- flextable( head( iris ) )
ft <- set_header_df(x = ft, mapping = data.frame(keys = names1, values = names2, stringsAsFactors = FALSE),
              key = "keys" )

# the following call is needed as header formats have been 
# replaced by vanilla formats when set_header_df() has been called
ft <- theme_booktabs(ft) 
ft

Murky

Thanks for a prompt answer and a great package! – Karolyn

Answer 2

OK, after a couple edits I hope this works for you.

Your method seems plenty fine as well.

names1 <- c("Sepal.Length", "Sepal.Width", "Petal.Length", "Petal.Width", "Species")
names2 <- c('SL','SW','PL','PW','SPECIES')

ft <- flextable( head( iris ),
                   col_keys = names1 )

oldHeaders <- names1
newHeaders <- names2

headerlist <- setNames(as.list(newHeaders), 
                       oldHeaders)

ft <- do.call(set_header_labels, c(list(x = ft, top = F), headerlist))
ft

Kee

Thank you, this is great. I accepted the other answer as it came from the package creator and should therefore be considered technically correct. – Karolyn

No problem @J.Con. The other answer is more straightforward and from the horse's mouth, as they say. And thanks for the question. I've been looking for a package like this. – Kee

This answer helped me a lot. I recommend using the tidyverse package with flextable. – Karolyn