r - GGally::ggpairs plot without gridlines when plotting correlation coefficient

Question

GGally::ggpairs plots nice graphs like following one. Only thing I seek to refine it even more is to remove all gridlines in upper part of plot, where is correlation coefficient. An maybe also draw rectangle around each upper graph.

library("GGally")
data(iris)
ggpairs(iris[, 1:4], lower=list(continuous="smooth", params=c(colour="blue")),
  diag=list(continuous="bar", params=c(colour="blue")), 
  upper=list(params=list(corSize=6)), axisLabels='show')

Answer 1

查看这个相关问题和我的分叉回购。用于assignInNamespace修改ggally_cor功能，如上述问题所示。

唯一需要做的是修改theme调用：

  theme(legend.position = "none", 
        panel.grid.major = element_blank(), 
        axis.ticks = element_blank(), 
        panel.border = element_rect(linetype = "dashed", colour = "black", fill = NA))