How to specify a custom formatter function gt table grand summary? - r

Question

I'm trying to use a custom formatter function to format grand summary rows in gt table.
in the example below I was trying to use seconds_to_period from lubridate but I get
the error "**Error in stop_if_not_gt(data = data) : **
require(tidyverse)
require(lubridate)
sp500 %>%
dplyr::filter(
date >= "2015-01-05" &
date <="2015-01-16"
) %>%
dplyr::arrange(date) %>%
dplyr::mutate(
week = paste0(
"W", strftime(date, format = "%V"))
) %>%
dplyr::select(-adj_close, -volume) %>%
gt(
rowname_col = "date",
groupname_col = "week"
) %>%
grand_summary_rows(
columns = vars(open, high, low, close),
fns = list(
min = ~min(.),
max = ~max(.),
avg = ~mean(.)),
formatter = fmt(fns=seconds_to_period),
use_seps = FALSE
)
I've tried some variations like formatter = fmt(columns=vars(min),fns=seconds_to_period) with no sucess.
Thanks

Answer 1

Since you didn't share the seconds_to_period function, my guess is you are trying a transformation/computation with a format function. As far as I know, that's not possible. formatter arg allows you to apply a format to an already computed summary cell. And the sintaxys to pass the fmt* arguments inside grand_summary_rows is quite different. Instead of passing them inside parenthesis fmt* function, you should pass them as grand_summary_rows arguments:
df |>
gt()|>
grand_summary_rows(
columns = vars(open, high, low, close),
fns = list(
min = ~min(.),
max = ~max(.),
avg = ~mean(.)),
formatter = fmt_number,
decimals = 1,
use_seps = FALSE
)
In any case, in your code you're passing use_steps, which is a fmt_number argument, to a fmt function, which does not admit it. Take a look at fmt docummentation.
Anyway, it's not clear what you a are trying to accomplish. OHLC are prices data. And I guess from your function name (seconds_to_period) that you're trying to give this prices data a time class format. If the case, you should compute/transform the content before trying to format it.