R ggplpot（）：较粗的X和Y轴

Question

I have data that crosses the x-axis and I am trying to darken the axes to make them more apparent in the chart. The code I am using just keeps darkening the lines on the bottom and left of the box around the chart and not the axes themselves. What am I missing? Code and image are below.

ggplot() +
  geom_line(data=eff, aes(EaR, Forward.Cost), color=rgb(187,8,38, max=255)) +
  geom_line(data=arbitrary, aes(EaR, Forward.Cost), color=rgb(196,165,96, max=255)) +
  ggtitle("Efficient Frontier \n") +
  labs(x="EaR", y="Forward Cost") +
  theme_bw() +
  theme(axis.line = element_line(size = 1, color = rgb(0,0,0,max=255))) +
  geom_point(data=eff, aes(EaR, Forward.Cost),size=2, color=rgb(187,8,38,max=255)) +
  geom_point(data=arbitrary, aes(EaR, Forward.Cost),size=2, color=rgb(196,165,96,max=255))

Answer 1

For backgrounds and borders.

gg+theme(panel.border = element_rect(linetype = "solid", colour = "black", size=5))+

rest of your code

Answer 2

There is an issue with the argument "panel.border" in ggplot2 . The users etiennebr and nfdisco have detected that, even when printing in PDF, lines showed discrepancies in thickness between different axes.

Therefore, there seems to be very little workarounds to this persistent issue. You may want to try different values for the line thickness, for png(res=xxx) , or ggsave(dpi=xxx) , to see if there are any significant changes, as suggested by the collaborator wch.