In ggplot2, is it good practice to ungroup the data before plotting?

davidhodge931 · June 11, 2023, 11:18pm

In ggplo2, is it good practice to ungroup the data before plotting?

I think I came across this a while ago, but not sure if it is still valid

martin.R · June 12, 2023, 8:52am

I would say it is.

In fact I'd always ungroup unless you are sure you want to retain the grouping because not doing so can cause unintended consequences.

davidhodge931 · June 12, 2023, 8:57pm

Looks like based on a comment by one of the maintainers that ggplot2 is not aware of group_by??

github.com/tidyverse/ggplot2

Feature Request - Wouldn't it be cool if ggplot2 recognized `dplyr::group_by()`?

opened 09:14PM - 21 Aug 19 UTC

closed 11:19AM - 01 Oct 19 UTC

ghost

I've got a feature request to give ggplot2 the ability to recognize `dplyr::grou…p_by()`. ```r library(tidyverse) library(lubridate) library(stringr) df <- tibble(Date = as.Date(0:364, origin = "2017-07-01"), Value = rnorm(365)) %>% mutate(Year = str_sub(Date, 1, 4), MoFloor = floor_date(Date, unit = "month")) %>% group_by(Year, MoFloor) %>% mutate(MoAvgValue = mean(Value)) %>% ungroup() %>% group_by(Year) %>% mutate(MinMoFloor = min(MoFloor), MaxMoFloor = max(MoFloor), YearAvgValue = mean(MoAvgValue)) ``` Let's first plot the data frame above. ```r ggplot(df, aes(MoFloor, MoAvgValue, group = Year)) + facet_grid(~Year, scale = "free_x", space = "free_x") + geom_point() ``` [![plot1][1]][1] In my call to the `facet_grid()` function I added the arguments `scale = "free_x"` and `space = "free_x"` to get rid of empty white space on the plots. When I go ahead and add `geom_segment()`s based on `group_by()`d data, the `scale = "free_x"` and `space = "free_x"` arguments are negated. The empty white space reappears! ```r ggplot(df, aes(MoFloor, MoAvgValue, group = Year)) + facet_grid(~Year, scale = "free_x", space = "free_x") + geom_point() + geom_segment(data = df, aes(x = min(MinMoFloor), y = YearAvgValue, xend = max(MaxMoFloor), yend = YearAvgValue)) ``` [![plot2][2]][2] My `df` data frame is grouped by `Year`. The `geom_segment()` function does not recognize this when I enter (for example) the `x = min(MinMoFloor)` argument. `geom_segment()` is pulling the `min(MinMoFloor)` from the global column, instead of the grouped column. I know I could substitute a modified `geom_hline()` function instead of `geom_segment()` for a working solution, but my lines are sometimes diagonal. And sometimes I'll have 50+ of these facet panels in my visualization, so defining the values manually is not practical either. Thanks for considering this feature. [1]: https://i.stack.imgur.com/23YZ7.png [2]: https://i.stack.imgur.com/gETPE.png

system · July 3, 2023, 8:57pm

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