Remove a flextable columns after the flextable creation - flextable

Question

I create a flextable based on a csv file, I put some style on it, change some cells. Then I would like to remove a specific columns of this flextable before add it to a doc.
Is-there a way to create a copy of a flextable and specifying col_keys?
mydf <- GetData(....)
cols <- names(mydf)
myft <- flextable(mydf, col_keys = cols)
# Adding style to ft...
# ....
# Here I want to remove one column to the ft (and only here, not when first creating the ft)
# something as:
# ft <- CreateCopyOfFlextable(ft,cols[-which(cols=='COLB')])
#
my_doc <- read_docx()
my_doc <- my_doc %>% body_add_par("") %>%
body_add_flextable(value = ft)
print(my_doc, target = 'c:/temp/doc.docx')

Answer 1

I just had the same problem and had a devil of a time Googling for a solution. #David-Gohel truly has the answer here, but I feel the need to provide a similar solution with additional explanation.
My problem and the OPs is that we wanted to use the data from columns that wouldn't be displayed to influence the formatting of columns that will be displayed. The concept that was not initially obvious is that you can send a data frame to flextable with more columns than you intend to display (instead of displaying all and deleting them you've used them). Then, by using the col_keys argument, you can select only those columns that you want to display while keeping the remaining ones around for additional processing (e.g., for using compose(), paragraph(), or add_chunk()).
If I understand correctly, COLB is supposed to be a flag to indicate that certain rows of COLC should be modified. If so, then my solution looks like this:
library(flextable)
library(magrittr)
library(officer)
df <- data.frame(COLA=c('a', 'b', 'c'),
COLB=c('', 'changevalue', ''),
COLC=c(10, 12, 13))
ft <- flextable(df, col_keys = c("COLA", "COLC")) %>% # Retain but don't display COLB
compose(i = ~ COLB =='changevalue', # Use COLB for conditional modifications
j = "COLC",
value = as_paragraph(as_chunk('100')),
part = 'body') %>%
style(i = ~ COLB =='changevalue', # Use COLB for conditional formatting on COLC
j = "COLC",
pr_t = fp_text(color = "black",
font.size = 11,
bold = TRUE,
italic = FALSE,
underline = FALSE,
font.family = "Times New Roman"),
part = "body")
ft
And here's what the above code produces (e.g., the "changevalue" column is the trigger for conditionally inserting 100 in COLC and also for changing the formatting):

Answer 2

library(flextable)
library(magrittr)
library(officer)
df <- data.frame(COLA=c('a','b','c'),
COLB=c('','changevalue',''),
COLC=c(10,12,13))
ft<-flextable(df, col_keys = c("COLA", "COLB"))
ft <- ft %>%
style(i= ~ COLB=='changevalue',
pr_t=fp_text(color="black", font.size=11, bold=TRUE, italic=FALSE, underline=FALSE, font.family="Times New Roman"),part="body")
ft<-compose(ft, i=2, j="COLB", value = as_paragraph(as_chunk('100')),part = 'body')
ft

Answer 3

I'm styling another column based on COLB.
Here an example:
df <- data.frame(COLA=c('a','b','c'),COLB=c('','changevalue',''),COLC=c(10,12,13))
ft<-flextable(df)
ft <- ft %>% style(i=which(ft$body$dataset$COLB=='changevalue'),pr_t=fp_text(color="black", font.size=11, bold=TRUE, italic=FALSE, underline=FALSE, font.family="Times New Roman"),part="body")
ft<-compose(ft, i=2,j=3, value = as_paragraph(as_chunk('100')),part = 'body')
# now I want to remove the COLB columns as I don't need it anymore
# ???????
my_doc <- read_docx()
my_doc <- my_doc %>% body_add_par("") %>% body_add_flextable(value = ft)
print(my_doc, target = 'c:/temp/orliange_p/sample.docx') %>% invisible()