# How to sum two variables in a horizontal bar chart?

Drawing blank here. I would like a chart with three bars for the three types with each bar being a sum of the total of each type. A should be 27; B, 36; and C, 11.

My data and attempt:

``````library(tidyverse)

type <- c("A", "A", "A", "A", "B", "B", "B", "B", "B", "B", "C", "C")
quant <- c("2", "9", "5", "11", "2", "9", "12", "2", "6", "5", "5", "6")

dat <- data.frame(type, quant)

ggplot(dat, aes(y=type)) + geom_bar()

``````

Thanks,
Jeff

I find it easiest to summarize the data before passing it to ggplot(). Also, putting quotes around numeric values adds the extra step of converting them to numbers, so I deleted the quotes.

``````library(ggplot2)
library(dplyr)

type <- c("A", "A", "A", "A", "B", "B", "B", "B", "B", "B", "C", "C")
quant <- c(2, 9, 5, 11, 2, 9, 12, 2, 6, 5, 5, 6)

dat <- data.frame(type, quant)
dat |> group_by(type) |> summarize(Total = sum(quant)) |>
ggplot(aes(x = Total, y=type)) + geom_col()
`````` Created on 2023-03-01 with reprex v2.0.2

1 Like

You need calculate the sum and next make the plot

``````type <- c("A", "A", "A", "A", "B", "B", "B", "B", "B", "B", "C", "C")
quant <- c("2", "9", "5", "11", "2", "9", "12", "2", "6", "5", "5", "6")

dat <- data.frame(type, quant)

# Convert quant to numeric
dat\$quant <- as.numeric(dat\$quant)

# Calculate the total for each type
total <- aggregate(dat\$quant, by=list(dat\$type), FUN=sum)

# Set column names
colnames(total) <- c("type", "total")

# Create bar plot
ggplot(total, aes(x=type, y=total, fill=type)) +
geom_bar(stat="identity") +
labs(title="Total by Type", x="Type", y="Total")
``````

1 Like

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