13.2 条形图

日常使用最多的图形无外乎散点图、柱形图（分组、堆积、百分比堆积等）

# 简单条形图
library(data.table)
diamonds <- as.data.table(diamonds)

p11 <- diamonds[, .(cnt = .N), by = .(cut)] %>%
  plot_ly(x = ~cut, y = ~cnt, type = "bar") %>%
  add_text(
    text = ~ scales::comma(cnt), y = ~cnt,
    textposition = "top middle",
    cliponaxis = FALSE, showlegend = FALSE
  )
# 分组条形图
p12 <- plot_ly(diamonds,
  x = ~cut, color = ~clarity,
  colors = "Accent", type = "histogram"
) 
# 堆积条形图
p13 <- plot_ly(diamonds,
  x = ~cut, color = ~clarity,
  colors = "Accent", type = "histogram"
) %>%
  layout(barmode = "stack")
# 百分比堆积条形图
# p14 <- plot_ly(diamonds,
#   x = ~cut, color = ~clarity,
#   colors = "Accent", type = "histogram"
# ) %>%
#   layout(barmode = "stack", barnorm = "percent") %>%
#   config(displayModeBar = F)

# 推荐使用如下方式绘制堆积条形图
dat = diamonds[, .(cnt = length(carat)), by = .(clarity, cut)] %>%
  .[, pct := round(100 * cnt / sum(cnt), 2), by = .(cut)]

p14 <- plot_ly(
  data = dat, x = ~cut, y = ~pct, color = ~clarity,
  colors = "Set3", type = "bar"
) %>%
  layout(barmode = "stack")

htmltools::tagList(p11, p12, p13, p14)