我正在使用knitr创建一个包含多个图像的markdown文件。因为我不想每次都说出这条路，所以我希望它是相对的。
mainDir <- ~/Documents/R/Images/
subDir <- Logo
color <- blue
现在我想添加'.png'来打印实际图像。而且我不想将颜色更改为<- blue.png，因为我在代码的其他部分使用变量'blue'。
img1 <- rasterGrob(as.raster(readPNG(file.path(mainDir, subDir, color, ".png"))), interpolate = FALSE)
我收到以下错误： readPNG中的错误（file.path（mainDir，subDir，img，“。png”））： 无法打开/Documents/R/Images/Logo/blue/.png
如何删除最后一个“/”，以便它是'blue.png'而不是blue / .png？
答案 0 :(得分：2)
怎么样：
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</div>结果： ＆＃34;〜/文档/ R /图像/标志/ blue.png＆＃34;
答案 1 :(得分：2)
您可以使用paste函数将文件扩展名连接到路径字符串。
img1 <- rasterGrob(as.raster(readPNG(paste(file.path(mainDir, subDir, color), ".png", sep = ""))), interpolate = FALSE)
http://stat.ethz.ch/R-manual/R-patched/RHOME/library/base/html/paste.html
此外，/上不需要尾随mainDir <- "~/Documents/R/Images"，因为在添加子目录时它会重复。