par(mar=c(1,1,1,1))
col_blues <- rep(1, 50)
names(col_blues) <- unique(gsub('[0-9]+', '', colors()[grep(colors(), pattern="gray")]))
pie(col_blues,col=names(col_blues),radius=.8, cex=.65, clockwise=T) 

#clockwise=T 順時針方向排列（TRUE）
?blue
## No documentation for 'blue' in specified packages and libraries:
## you could try '??blue'
?gray
## starting httpd help server ... done

gray{grDevices}.

?pie
set.seed(32452)
greys <- grep("^grey", colours(), value = TRUE)
sample(greys, 50, replace=FALSE)
##  [1] "grey38" "grey73" "grey81" "grey46" "grey34" "grey99" "grey70" "grey67"
##  [9] "grey41" "grey62" "grey20" "grey89" "grey71" "grey75" "grey9"  "grey39"
## [17] "grey4"  "grey63" "grey74" "grey91" "grey60" "grey19" "grey36" "grey68"
## [25] "grey26" "grey79" "grey33" "grey23" "grey14" "grey72" "grey7"  "grey35"
## [33] "grey59" "grey92" "grey10" "grey11" "grey42" "grey15" "grey13" "grey76"
## [41] "grey40" "grey54" "grey5"  "grey30" "grey17" "grey95" "grey58" "grey93"
## [49] "grey29" "grey1"
par(mar=c(1,1,1,1))
col_gray <- rep(1, 50)
names(col_gray) <- unique(gsub('[0-50]+', 
                                '', 
                                colors()[grep(colors(), pattern="gray")]))
pie(col_gray, 
    col=names(col_gray), 
    radius=.8, cex=.65, clockwise=T)

par(mar=c(1,1,1,1))
col_gray <- rep(1, 50)
names(col_gray) <- unique(gsub('[0-294]+', 
                                '', 
                                colors()[grep(colors(), pattern="gray")]))
pie(col_gray, 
    col=names(col_gray), 
    radius=.8, cex=.65, clockwise=T)

par(mar=c(1,1,1,1))

palette(gray(0:50 / 50)) #修改調色盤的顏色
pie(rep(1,50), col=palette(), border = palette(), main = "Gray")