R Plotly与Shiny可视化求助：异常边距及双X轴设置

Hey there! Let's work through your two Plotly + Shiny visualization issues step by step. I’ve reviewed your code and identified key tweaks to fix both the margin problem and add dual X-axes.

1. Fix Excessive Top/Bottom Margins for Large Y-Axis Datasets #

First, I spotted a typo in your yaxis configuration: you used categoryarray = ~qt, but your data frame doesn’t have a qt column—this should be ~y instead! This mistake could throw off Y-axis rendering and contribute to weird spacing. Additionally, fixed top/bottom margins (t=100, b=50) don’t scale well when you have 40+ Y-axis items. We’ll adjust these to be dynamic based on the number of rows in your data, plus tweak annotation font size to avoid layout miscalculations.

2. Add X-Axis to Both Top and Bottom of the Chart #

To display the X-axis on both the top and bottom, we’ll add a second X-axis (xaxis2) that overlays the primary X-axis and sits at the top. We’ll mirror the primary X-axis settings to keep styling consistent.

Full Revised Code #

y <- c("q1", "q2", "q3", "q4", "q5", "q6", "q7") 
x1 <- c(20, 10, 15, 15, 20, 10, 15) 
x2 <- c(10, 20, 20, 10, 10, 30, 10) 
x3 <- c(10, 10, 5, 10, 10, 5, 5) 
x4 <- c(20, 25, 25, 35, 55, 40, 35) 
x5 <- c(40, 35, 35, 30, 5, 15, 35) 
num <- c(1,3,5,6,7,2,4) 
df <- data.frame(y, x1, x2, x3, x4, x5, num) 

plot_ly(df[order(-xtfrm(df$num)),]) %>% 
  add_trace(x = ~x1, y = ~y, marker = list(color = 'rgb(202,0,32)'), type = 'bar', orientation = 'h') %>% 
  add_trace(x = ~x2, y = ~y, marker = list(color = 'rgb(244,165,130)'), type = 'bar', orientation = 'h') %>% 
  add_trace(x = ~x3, y = ~y, marker = list(color = 'rgb(223,223,223)'), type = 'bar', orientation = 'h') %>% 
  add_trace(x = ~x4, y = ~y, marker = list(color = 'rgb(146,197,222)'), type = 'bar', orientation = 'h') %>% 
  add_trace(x = ~x5, y = ~y, marker = list(color = 'rgb(5,113,176)'), type = 'bar', orientation = 'h') %>% 
  layout(
    title="mytitle",
    xaxis = list(
      title = "", 
      showticklabels = TRUE, 
      zeroline = FALSE, 
      domain = c(0.15, 1),
      anchor = 'y'  # Link primary X-axis to main Y-axis
    ),
    xaxis2 = list(
      title = "", 
      showticklabels = TRUE, 
      zeroline = FALSE, 
      domain = c(0.15, 1),
      overlaying = 'x',  # Overlay on primary X-axis
      side = 'top'  # Position at the top of the chart
    ),
    yaxis = list(
      title = "", 
      showticklabels = FALSE, 
      zeroline = FALSE, 
      categoryorder = 'array', 
      categoryarray = ~y  # Fixed typo here
    ),
    barmode = 'relative',
    paper_bgcolor = 'rgb(248, 248, 255)',
    plot_bgcolor = 'rgb(248, 248, 255)',
    autosize=T,
    # Dynamic margins: shrink top/bottom when >40 Y-axis items
    margin = list(
      l = 150, 
      r = 10, 
      t = ifelse(nrow(df) > 40, 50, 100), 
      b = ifelse(nrow(df) > 40, 30, 50), 
      pad=4
    ),
    showlegend=F
  ) %>% 
  # Adjusted font size to prevent layout glitches
  add_annotations(
    xref = 'paper', 
    yref = 'y', 
    x = 0.14, 
    y = df$y, 
    xanchor = 'right', 
    text = df$y, 
    font = list(family = 'Arial', size = 10, color = 'rgb(67, 67, 67)'), 
    showarrow = FALSE, 
    align = 'right'
  )

内容的提问来源于stack exchange，提问作者dorayin