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Working with Charts

Source: vignettes/charts.Rmd
charts.Rmd

Overview

Charts in rpptx embed a real Excel workbook inside the .pptx file — exactly as PowerPoint does. The workflow is:

  1. Create a CategoryChartData (or XyChartData / BubbleChartData) object
  2. Add categories and series
  3. Call slide$shapes$add_chart() with an XL_CHART_TYPE constant

Category charts (bar, column, line, pie, …)

Clustered column chart 

r <- blank_slide()
slide <- r$slide

cd <- CategoryChartData$new()
cd$categories <- c("Q1", "Q2", "Q3", "Q4")
cd$add_series("Revenue",  c(120, 145, 132, 178))
cd$add_series("Expenses", c(95,  110, 105, 130))

chart_shape <- slide$shapes$add_chart(
  XL_CHART_TYPE$COLUMN_CLUSTERED,
  left   = Inches(0.5),
  top    = Inches(0.5),
  width  = Inches(9),
  height = Inches(6),
  chart_data = cd
)
chart_shape$shape_type == MSO_SHAPE_TYPE$CHART
#> [1] TRUE

Bar chart (horizontal) 

r <- blank_slide()
slide <- r$slide

cd <- CategoryChartData$new()
cd$categories <- c("Product A", "Product B", "Product C")
cd$add_series("Units sold", c(450, 320, 580))

slide$shapes$add_chart(
  XL_CHART_TYPE$BAR_CLUSTERED,
  Inches(0.5), Inches(0.5), Inches(9), Inches(6), cd
)
#> <Chart>  "Chart 2"  9.00×6.00 in  @ 0.50, 0.50 in

Line chart 

r <- blank_slide()
slide <- r$slide

cd <- CategoryChartData$new()
cd$categories <- month.abb
cd$add_series("2023", c(40, 45, 55, 60, 70, 75, 80, 78, 65, 55, 48, 42))
cd$add_series("2024", c(42, 48, 58, 65, 72, 80, 85, 82, 70, 60, 52, 45))

slide$shapes$add_chart(
  XL_CHART_TYPE$LINE,
  Inches(0.5), Inches(0.5), Inches(9), Inches(6), cd
)
#> <Chart>  "Chart 2"  9.00×6.00 in  @ 0.50, 0.50 in

Pie chart 

r <- blank_slide()
slide <- r$slide

cd <- CategoryChartData$new()
cd$categories <- c("North", "South", "East", "West")
cd$add_series("Market share", c(35, 25, 20, 20))

slide$shapes$add_chart(
  XL_CHART_TYPE$PIE,
  Inches(1), Inches(0.5), Inches(8), Inches(6), cd
)
#> <Chart>  "Chart 2"  8.00×6.00 in  @ 1.00, 0.50 in

Area chart 

r <- blank_slide()
slide <- r$slide

cd <- CategoryChartData$new()
cd$categories <- paste0("Week ", 1:8)
cd$add_series("Team A", c(10, 15, 13, 20, 18, 22, 25, 24))
cd$add_series("Team B", c(8,  12, 10, 16, 14, 18, 20, 19))

slide$shapes$add_chart(
  XL_CHART_TYPE$AREA,
  Inches(0.5), Inches(0.5), Inches(9), Inches(6), cd
)
#> <Chart>  "Chart 2"  9.00×6.00 in  @ 0.50, 0.50 in

Available chart types

Some commonly used XL_CHART_TYPE constants:

Constant Description
COLUMN_CLUSTERED Clustered column (vertical bars)
COLUMN_STACKED Stacked column
COLUMN_STACKED_100 100% stacked column
BAR_CLUSTERED Clustered bar (horizontal)
BAR_STACKED Stacked bar
LINE Line chart
LINE_MARKERS Line with markers
LINE_STACKED Stacked line
PIE Pie chart
PIE_EXPLODED Exploded pie
AREA Area chart
AREA_STACKED Stacked area
XY_SCATTER Scatter (XY)
BUBBLE Bubble chart
DOUGHNUT Doughnut
RADAR Radar / spider

XY (scatter) charts

XY charts need XyChartData which accepts (x, y) pairs per series:

r <- blank_slide()
slide <- r$slide

cd <- XyChartData$new()
cd$add_series("Series 1",
  x_values = c(1, 2, 3, 4, 5),
  y_values = c(2.1, 3.8, 5.2, 7.1, 9.0)
)
cd$add_series("Series 2",
  x_values = c(1, 2, 3, 4, 5),
  y_values = c(1.5, 2.9, 4.1, 5.8, 7.3)
)

slide$shapes$add_chart(
  XL_CHART_TYPE$XY_SCATTER,
  Inches(0.5), Inches(0.5), Inches(9), Inches(6), cd
)
#> <Chart>  "Chart 2"  9.00×6.00 in  @ 0.50, 0.50 in

Accessing chart properties

After adding a chart, retrieve the Chart object to adjust its properties:

r <- blank_slide()
slide <- r$slide

cd <- CategoryChartData$new()
cd$categories <- c("A", "B", "C")
cd$add_series("S1", c(1, 2, 3))

chart_shape <- slide$shapes$add_chart(
  XL_CHART_TYPE$COLUMN_CLUSTERED,
  Inches(0.5), Inches(0.5), Inches(9), Inches(6), cd
)

chart <- chart_shape$chart
class(chart)   # "Chart"
#> [1] "Chart" "R6"

Chart title 

chart$has_title <- TRUE
chart$chart_title$text_frame$text <- "My Chart Title"

Legend 

chart$has_legend <- TRUE
chart$legend$position <- XL_LEGEND_POSITION$BOTTOM
chart$legend$include_in_layout <- FALSE

Legend positions: TOP, BOTTOM, LEFT, RIGHT, CORNER.

Axes 

cat_axis <- chart$category_axis
val_axis  <- chart$value_axis

# Axis visibility
cat_axis$visible <- TRUE
val_axis$visible <- TRUE

# Tick label position
cat_axis$tick_label_position <- "low"
val_axis$tick_label_position <- "nextTo"

# Scale
val_axis$minimum_scale <- 0
val_axis$maximum_scale <- 200

Number format

Axis tick labels can use any Excel number format string:

val_axis$tick_labels$number_format <- "0.0%"   # percentage
val_axis$tick_labels$number_format <- "#,##0"  # thousands separator
val_axis$tick_labels$number_format <- "General" # default

Tick marks 

val_axis$major_tick_mark <- XL_TICK_MARK$OUTSIDE
val_axis$minor_tick_mark <- XL_TICK_MARK$NONE
cat_axis$major_tick_mark <- XL_TICK_MARK$CROSS

Tick mark constants: NONE, INSIDE, OUTSIDE, CROSS.

Gridlines 

val_axis$has_major_gridlines <- TRUE
val_axis$has_minor_gridlines <- FALSE

Reverse axis order 

val_axis$reverse_order <- TRUE   # descending values
cat_axis$reverse_order <- FALSE  # ascending categories

Data labels 

plot <- chart$plots[[1]]
plot$has_data_labels <- TRUE
dls <- plot$data_labels
dls$show_value         <- TRUE
dls$show_category_name <- FALSE
dls$show_series_name   <- FALSE

Series formatting

Each series exposes a format property with fill and line sub-objects (same as shape formatting):

series <- chart$plots[[1]]$series[[1]]
series$format$fill$solid()
series$format$fill$fore_color$rgb <- RGBColor(0x4F, 0x81, 0xBD)
series$format$line$width <- Pt(1.5)
series$format$line$color$rgb <- RGBColor(0x1F, 0x49, 0x7D)

Individual data points can also be formatted:

pt <- series$data_points[[2]]   # second point
pt$format$fill$solid()
pt$format$fill$fore_color$rgb <- RGBColor(0xFF, 0x00, 0x00)

Chart area formatting

The chart and plot areas have a format property:

chart$format$fill$solid()
chart$format$fill$fore_color$theme_color <- MSO_THEME_COLOR$ACCENT_1
chart$format$line$width <- Pt(0.5)

Chart type reference 

# All available chart types
length(XL_CHART_TYPE)   # 73+
#> [1] 73
# Common types
XL_CHART_TYPE$COLUMN_CLUSTERED
XL_CHART_TYPE$BAR_CLUSTERED
XL_CHART_TYPE$LINE
XL_CHART_TYPE$PIE
XL_CHART_TYPE$AREA
XL_CHART_TYPE$XY_SCATTER
XL_CHART_TYPE$BUBBLE
XL_CHART_TYPE$DOUGHNUT
XL_CHART_TYPE$RADAR

Full example 

prs    <- pptx_presentation()
layout <- prs$slide_layouts[[6]]
slide  <- prs$slides$add_slide(layout)

# Build chart data
cd <- CategoryChartData$new()
cd$categories <- c("Jan", "Feb", "Mar", "Apr", "May", "Jun")
cd$add_series("Actual",   c(120, 135, 128, 155, 162, 175))
cd$add_series("Forecast", c(115, 130, 140, 150, 165, 180))

# Add chart
cs <- slide$shapes$add_chart(
  XL_CHART_TYPE$LINE_MARKERS,
  Inches(0.5), Inches(0.5),
  Inches(9),   Inches(6.5),
  cd
)

# Decorate
ch <- cs$chart
ch$has_title <- TRUE
ch$chart_title$text_frame$text <- "H1 Performance"
ch$has_legend <- TRUE
ch$legend$position <- XL_LEGEND_POSITION$BOTTOM

tmp <- tempfile(fileext = ".pptx")
prs$save(tmp)