Alluvial 1st version

R/alluvial.R

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+#' @title Simple alluvial chart
+#'
+#' @param df A data frame.
+#' @param from A character column of upstream stratum.
+#' @param to A character column of downstream stratum.
+#' @param value A numeric column of values.
+#' @param group The grouping column to fill the alluvium with.
+#' @param alpha Fill transparency. Default to 0.5.
+#' @param from_levels Order by given from levels?
+#' @param value_title The value/y scale title. Default to NULL.
+#' @param group_title The group title. Default to NULL.
+#' @param title Plot title. Default to NULL.
+#' @param subtitle Plot subtitle. Default to NULL.
+#' @param caption Plot caption. Default to NULL.
+#' @param rect_color Stratum rectangles' fill color.
+#' @param rect_border_color Stratum rectangles' border color.
+#' @param rect_text_color Stratum rectangles' text color.
+#' @param theme Whatever theme. Default to theme_reach().
+#'
+#' @return A donut chart to be used parsimoniously
+#'
+#' @export
+alluvial <- function(
+    df,
+    from,
+    to,
+    value,
+    group = NULL,
+    alpha = 0.5,
+    from_levels = NULL,
+    value_title = NULL,
+    group_title = NULL,
+    title = NULL,
+    subtitle = NULL,
+    caption = NULL,
+    rect_color = cols_reach("white"),
+    rect_border_color = cols_reach("main_grey"),
+    rect_text_color = cols_reach("main_grey"),
+    theme = theme_reach(axis_y = FALSE,
+                        legend_position = "none")
+){
+
+  if(!is.null(from_levels)) df <- dplyr::mutate(df, "{{from}}" := factor({{ from }}, levels = from_levels))
+
+  # General mapping
+  g <- ggplot2::ggplot(
+    data = df,
+    mapping = ggplot2::aes(
+      y = {{ value }},
+      axis1 = {{ from }},
+      axis3 = {{ to }}
+      )
+    )
+
+  # Add alluvium
+  g <- g +
+    ggalluvial::geom_alluvium(
+      ggplot2::aes(
+        fill = {{ group }},
+        color = {{ group }}
+      ),
+      alpha = alpha)
+
+  # Add stratum
+  g <- g +
+    ggalluvial::geom_stratum(
+      fill = rect_color,
+      color = rect_border_color
+    )
+
+  # Add stratum text
+
+  stratum <- ggalluvial::StatStratum
+
+  g <- g +
+    ggplot2::geom_text(
+      stat = stratum,
+      ggplot2::aes(label = ggplot2::after_stat(!!rlang::sym("stratum"))),
+      color = cols_reach("main_grey")
+  )
+
+
+  # Add title, subtitle, caption, x_title, y_title
+  g <- g + ggplot2::labs(
+    y = value_title,
+    title = title,
+    subtitle = subtitle,
+    caption = caption,
+    fill = group_title,
+    color = group_title
+  )
+
+  # Remove x-axis
+  g <- g + ggplot2::theme(
+    axis.line.x = ggplot2::element_blank(),
+    axis.ticks.x = ggplot2::element_blank(),
+    axis.text.x = ggplot2::element_blank(),
+    axis.title.x = ggplot2::element_blank()
+  )
+
+  g <- g + theme
+
+  return(g)
+}