多亏了一些帮助，我设法解决了这个问题，问题是我没有在我的组变量中提供一个代表组的颜色图。所以我在函数外创建了一个函数，如下所示：

colour_map <- c("group1" = "#colour1",
                "group2" = "#colour2", 
                "group3" = "#colour3")

这是函数的一部分，其中进行了更改，它的行ggplot2::geom_col(fill = colour_mapping[group])稍后将调用颜色Map。

for (group in unique_groups) {
      plot <- data %>%
        dplyr::filter(!!group_sym == group) %>%
        dplyr::count(plot_date) %>%
        ggplot2::ggplot(ggplot2::aes(x = plot_date, y = n)) +
        ggplot2::geom_col(fill = colour_mapping[group]) +
        HelpR::theme_microsoft() +
        ggplot2::scale_x_date(date_breaks = "1 months", date_labels = "%d-%b") +
        ggplot2::theme(legend.position = "none",
                       axis.text.x = element_text(angle = 45),
                       panel.grid = element_blank()) +
        ggplot2::labs(title = paste("Topic Volume over Time -", group), x = NULL, y = "Number of Posts")

      plots[[group]] <- plot
    }
    return(plots)

这意味着当想要渲染绘图列表时，现在可以像这样使用此函数：

plot_group_vot(data = data, group_var = group_var, date_var = date, unit = "day", plot_type = "list", colour_mapping = colour_map)

更新后的函数现在如下所示：

plot_group_vot <- function(data = data,
                           group_var,
                           date_var,
                           unit = c("day", "week", "month", "quarter", "year"),
                           nrow = 2,
                           plot_type = c("facet", "list"),
                           colour_mapping = NULL) {

  unit <- match.arg(unit)

  date_sym <- rlang::ensym(date_var)
  group_sym <- rlang::ensym(group_var)

  if (plot_type == "facet") {
    data <- data %>% dplyr::mutate(plot_date = lubridate::floor_date(!!date_sym, unit = unit),
                                   facet_var = !!group_sym)

    plot <- data %>%
      dplyr::count(plot_date, facet_var) %>%
      ggplot2::ggplot(ggplot2::aes(x = plot_date, y = n, fill = facet_var)) +
      ggplot2::geom_col() +
      HelpR::theme_microsoft() +
      ggplot2::scale_x_date(date_breaks = "1 months", date_labels = "%d-%b") +
      ggplot2::theme(legend.position = "none",
                     axis.text.x = element_text(angle = 45),
                     panel.grid = element_blank()) +
      ggplot2::labs(title = "Topic Volume over Time", x = NULL, y = "Number of Posts") +
      ggplot2::facet_wrap(~facet_var, nrow = nrow)

    print(plot)

  } else if (plot_type == "list") {
    data <- data %>% dplyr::mutate(plot_date = lubridate::floor_date(!!date_sym, unit = unit),
                                   facet_var = !!group_sym)

    unique_groups <- data %>% pull(!!group_sym) %>% unique()
    plots <- list()

    for (group in unique_groups) {
      plot <- data %>%
        dplyr::filter(!!group_sym == group) %>%
        dplyr::count(plot_date) %>%
        ggplot2::ggplot(ggplot2::aes(x = plot_date, y = n)) +
        ggplot2::geom_col(fill = colour_mapping[group]) +
        HelpR::theme_microsoft() +
        ggplot2::scale_x_date(date_breaks = "1 months", date_labels = "%d-%b") +
        ggplot2::theme(legend.position = "none",
                       axis.text.x = element_text(angle = 45),
                       panel.grid = element_blank()) +
        ggplot2::labs(title = paste("Topic Volume over Time -", group), x = NULL, y = "Number of Posts")

      plots[[group]] <- plot
    }
    return(plots)

  } else {
    stop("Invalid plot_type argument. Try 'facet' or 'list'.")
  }
}