R ggplot2绘制各财年部门总支出折线图问题求助

我需要生成一张展示各财年（Fiscal.Year）各部门总支出的简洁折线图。目前运行R代码生成的图表不符合预期，希望能达到Excel生成的图表样式。

以下是我的代码：

# Convert negative amounts to absolute values
Sac$Amount <- ifelse(Sac$Amount < 0, abs(Sac$Amount), Sac$Amount)

# Get unique departments
departments <- unique(Sac$Department)

# Create and save line plots for each department
for (dept in departments) {
  # Subset data for the current department
  dept_data <- Sac[Sac$Department == dept, ]

  # Create line plot
  p <- ggplot(dept_data, aes(x = Fiscal.Year, y = Amount)) +
    geom_line() +
    labs(x = "Fiscal Year", y = "Amount (Absolute)", title = paste("Department:", dept)) +
    scale_x_continuous(breaks = unique(dept_data$Fiscal.Year), labels = unique(dept_data$Fiscal.Year)) +
    scale_y_continuous(labels = function(x) format(x, scientific = FALSE)) +
    theme_minimal()

  # Save as PNG file in your RStudio directory
  filename <- paste("department_expenses_", gsub("[^A-Za-z0-9]", "", dept), ".png", sep = "")
  ggsave(filename, plot = p, width = 12, height = 8, units = "in", dpi = 300)
}

我是R新手，尝试通过谷歌、YouTube及ChatGPT解决问题均未成功，首次使用Stack Overflow，若有信息遗漏敬请谅解，恳请帮忙解决。

内容的提问来源于stack exchange，提问作者user25111710