如何从data.frame创建因子变量并在并排图上绘制列

df$col <- as.factor(df$col)

install.packages("ggplot2")
library(ggplot2)

p <- ggplot(data = df)

p <- p + geom_bar(aes(x = col1, fill = "col1"), position = "dodge")
p <- p + geom_bar(aes(x = col2, fill = "col2"), position = "dodge")

p <- p + scale_fill_manual(values = c("col1" = "blue", "col2" = "red"))

# 将列转换为因子变量
df$col1 <- as.factor(df$col1)
df$col2 <- as.factor(df$col2)

# 安装并加载ggplot2包
install.packages("ggplot2")
library(ggplot2)

# 创建基础图形对象
p <- ggplot(data = df)

# 添加柱状图层
p <- p + geom_bar(aes(x = col1, fill = "col1"), position = "dodge")
p <- p + geom_bar(aes(x = col2, fill = "col2"), position = "dodge")

# 设置填充颜色
p <- p + scale_fill_manual(values = c("col1" = "blue", "col2" = "red"))

# 显示图形
print(p)