图像从R markdown推出投影仪输出的幻灯片

I'm using R markdown v2 to create a beamer presentation. Most of my slides contain an image generated by ggplot, sometimes with explanatory text above that slide. I've found that I really have to individually tweak the size of each element (i.e. image, text, etc) on each slide to ensure that the image doesn't get pushed off the end of the slide.I'm using R markdown v2 to create a beamer pres