删除PNG绘图边距 [英] Remove PNG plot margins
本文介绍了删除PNG绘图边距的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
我正在尝试摆脱SpatialPolygons图的顶部和底部边距. 我尝试将页边距设置为c(0,0,0,0),但这只会更改左侧和右侧页边距.
I am trying to get rid of the top and bottom margins of a SpatialPolygons plot. I have tried setting the margins to c(0,0,0,0) but this only changes the left and right margins.
在RStudio中进行绘制时,顶部和底部边距为0,而左侧和右侧则不为
When plotting in RStudio, the top and bottom margins are 0 but the left and right are not.
library(sp)
coords <- cbind(c(631145, 631757, 631928, 631664, 631579, 631281),
c(6967640, 6967566, 6968027, 6967985, 6968141, 6968009))
poly <- Polygons(list(Polygon(coords)),"coords")
poly.sp <- SpatialPolygons(list(poly))
par(mar = rep(0, 4), xaxs='i', yaxs='i')
plot(poly.sp, bg="yellow")
png('poly.png')
par(mar = rep(0, 4), xaxs='i', yaxs='i')
plot(poly.sp, bg="yellow")
dev.off()
推荐答案
我解决了这个问题,方法是计算要绘制的多边形的纵横比,然后设置绘制的宽度和高度.
I solved the problem by calculating the aspect ratio of the polygon that I am trying to plot and then setting the plot width and height.
这可能不是最优雅的解决方案,但可以完成工作.
This might not be the most elegant solution but it does the job.
library(sp)
coords <- cbind(c(631145, 631757, 631928, 631664, 631579, 631281),
c(6967640, 6967566, 6968027, 6967985, 6968141, 6968009))
poly <- Polygons(list(Polygon(coords)),"coords")
poly.sp <- SpatialPolygons(list(poly))
width <- poly.sp@bbox[3] - poly.sp@bbox[1]
height <- poly.sp@bbox[4] - poly.sp@bbox[2]
aspect <- height / width
png('poly.png', width = 10, height = 10*aspect, units = 'in', res = 300)
par(mar = rep(0, 4), xaxs='i', yaxs='i')
plot(poly.sp, bg="yellow")
dev.off()
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