使用ggplot绘制点线组合图：月度X轴与聚合值除法Y轴实现

Let's walk through fixing your data, aggregating the values correctly, and building the plot you want step by step.

Step 1: Fix Data Creation & Cleaning #

Your original data has a couple of small issues we need to address first:

• The name column isn't defined, so I'll add a dummy column for completeness.
• The anzahl column contains empty strings, which we need to convert to numeric (replacing blanks with NA).

# Create reproducible test data
set.seed(123) 
minuten <- runif(10)
anzahl <- c("", "", "", "23", "", "3", "", "", "5", "56")
time <- factor(c("Jan", "Jan", "Jan", "Jan", "Feb", "Feb", "Mar", "Mar", "Mar", "Apr"))
name <- paste0("Item", 1:10) # Dummy name column
df2 <- data.frame(name, anzahl, minuten, stringsAsFactors = FALSE)

# Clean the anzahl column: convert blanks to NA and make numeric
df2$anzahl <- as.numeric(gsub("^$", NA, df2$anzahl))

Step 2: Aggregate Data by Month #

The key mistake in your original code is trying to calculate sums directly inside ggplot's aes()—this won't group values by month. Instead, we need to pre-aggregate the data to get the ratio of total minuten to total anzahl per month. Using dplyr makes this simple:

library(dplyr)

agg_df <- df2 %>%
  group_by(time) %>%
  summarise(
    total_minuten = sum(minuten, na.rm = TRUE),
    total_anzahl = sum(anzahl, na.rm = TRUE),
    ratio = total_minuten / total_anzahl
  ) %>%
  # Ensure months appear in chronological order
  mutate(time = factor(time, levels = c("Jan", "Feb", "Mar", "Apr")))

If you don't have dplyr installed, you can use base R instead:

# Base R aggregation method
total_minuten <- aggregate(minuten ~ time, data = df2, sum, na.rm = TRUE)
total_anzahl <- aggregate(anzahl ~ time, data = df2, sum, na.rm = TRUE)
agg_df_base <- merge(total_minuten, total_anzahl, by = "time")
agg_df_base$ratio <- agg_df_base$minuten / agg_df_base$anzahl
agg_df_base$time <- factor(agg_df_base$time, levels = c("Jan", "Feb", "Mar", "Apr"))

Step 3: Build the Point-Line Plot #

Now use the aggregated data to create your plot with ggplot2:

library(ggplot2)

ggplot(data = agg_df, aes(x = time, y = ratio, group = 1)) +
  geom_line(color = "#2c3e50", linewidth = 1) + # Custom line style
  geom_point(color = "#e74c3c", size = 3) + # Custom point style
  labs(
    x = "Month",
    y = "Total Minutes / Total Count",
    title = "Monthly Ratio of Total Minutes to Total Count"
  ) +
  theme_minimal()

Key Notes: #

• group = 1 in the aes() is critical—it tells ggplot to connect all points into a single line (since time is a factor, without this, no line will be drawn).
• Pre-aggregating ensures we calculate the ratio per month, not across all rows.
• Ordering the time factor guarantees months show up in the correct order on the X-axis.

内容的提问来源于stack exchange，提问作者Anonymous