按组绘制时收到意外错误

正如@Arun在那发现的那样，似乎RStudio的本机图形设备在某种程度上被用于评估 j 和 by 时创建的不同子组的不断变化的指针所绊倒.存在，这使其适合于每次都简单地 copy 复制所有 .SD 的变通方法，例如: points(复制(季节)，复制(gini)，col = cols [.BY $ sport])行数(复制(季节)，复制(five_yr_ma)，col = cols [.BY $ sport]，lwd = 3) 或 x<-复制(.SD)with(x，{points(season，gini，cols = cols [.BY $ sport]);行数(复制(季节)，复制(five_yr_ma)，col = cols [.BY $ sport]，lwd = 3)}) 这两种方法都对我有用(由于子组很小，因此这里没有计算效率方面的问题-我们可以复制而不会显着影响性能)这是 data.table上的#1524 /code> GitHub页面，我已经在此错误报告；如果推送了修复程序，则会对此进行更新.Sorry for the massive data dump but I can't reproduce this on the subsets of the data I've tried. Copy-pasted the dput of the data (165 obs., not crazy) to this Gist.I'm trying to plot the data in DT by sport, according to:Create empty plot with proper limits to accommodate all dataPlot the column gini as a scatterplot, with colors varying by sportPlot the column five_year_ma as a line, with color matching that in 2.This should be simple and I've done things like it before. Here's what should work:#empty plot with proper axesDT[ , plot( NA, ylim = range(gini), xlim = range(season), xlab = "Season", ylab = "Gini", main = "Comparison of Gini Coefficient Across Sports")]#pick colors for each sportcols <- c(NHL="black", NBA="red")DT[ , by = sport, { #add points to current plot points(season, gini, col = cols[.BY$sport]) #add lines to current plot lines(season, five_yr_ma, col = cols[.BY$sport], lwd = 3)}]But this gives me output/error:# Empty data.table (0 rows) of 1 col: sportError: x and y lengths differ in plot.xy()This is strange. If we skip the grouping and just do it manually, it works perfectly fine:all_sports[sport == "NBA", { points(season, gini, col = "red") lines(season, five_yr_ma, col = "red", lwd = 3)}]all_sports[sport == "NHL", { points(season, gini, col = "black") lines(season, five_yr_ma, col = "black", lwd = 3)}]Moreover, even in the context of grouping, it's unclear why plot.xy has received arguments of different length -- if we make the following adjustment to force R to record the inputs just before they're sent, there doesn't appear to be any issue:all_sports[ , { cat("\n\nPlotting for sport: ", .BY$sport) points(x1 <- season, y1 <- gini, col = cols[.BY$sport]) lines(x2 <- season, y2 <- five_yr_ma, col = cols[.BY$sport], lwd = 3) cat("\npoints/season: ",length(x1), "\npoints/gini: ", length(y1), "\nlines/season: ", length(x2), "\nlines/five_yr_ma: ", length(y2))}, by = sport]Has output:# Plotting for sport: NHL# points/season: 98 # points/gini: 98 # lines/season: 98 # lines/five_yr_ma: 98# Plotting for sport: NBA# points/season: 67 # points/gini: 67 # lines/season: 67 # lines/five_yr_ma: 67What could be going on??Since it appears like this is not common across machines, here's my sessionInfo():R version 3.2.4 (2016-03-10)Platform: x86_64-pc-linux-gnu (64-bit)Running under: Ubuntu 14.04.3 LTSlocale: [1] LC_CTYPE=en_US.UTF-8 LC_NUMERIC=C LC_TIME=en_US.UTF-8 LC_COLLATE=en_US.UTF-8 [5] LC_MONETARY=en_US.UTF-8 LC_MESSAGES=en_US.UTF-8 LC_PAPER=en_US.UTF-8 LC_NAME=C [9] LC_ADDRESS=C LC_TELEPHONE=C LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C attached base packages:[1] stats graphics grDevices utils datasets methods base other attached packages:[1] data.table_1.9.7loaded via a namespace (and not attached):[1] rsconnect_0.4.1.11 tools_3.2.4 解决方案 Indeed, as @Arun points out, it seems this is a resurfacing of the (as yet unsolved) issue which was causing the error in this question:Values of the wrong group are used when using plot() within a data.table() in RStudioAs @Arun discovered there, it seems like RStudio's native graphics device is somehow getting tripped up by the changing pointers used for the different subgroups created when evaluating j when by is present, which lends itself to the workaround of simply copying all of .SD each time, like:points(copy(season), copy(gini), col = cols[.BY$sport])lines(copy(season), copy(five_yr_ma), col = cols[.BY$sport], lwd = 3)Orx <- copy(.SD)with(x, {points(season, gini, cols = cols[.BY$sport]); lines(copy(season), copy(five_yr_ma), col = cols[.BY$sport], lwd = 3)})Both of which worked for me (since the subgroups are so small, there's no computational efficiency concern at play here -- we can copy away without affecting performance noticeably).This is #1524 at the data.table GitHub page and I've filed this bug report at RStudio Support; will update this if a fix is pushed. 这篇关于按组绘制时收到意外错误的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！