我尝试创建一个简单的ROC曲线，执行以下操作：
library(ROCR)
data(ROCR.simple)
pred <- prediction( ROCR.simple$predictions, ROCR.simple$labels)
perf <- performance(pred,"tpr","fpr")
plot(perf)
然而，这给了我以下错误：
Error in UseMethod("prop_type") :
no applicable method for 'prop_type' applied to an object of class "performance"
有什么想法会导致这种情况吗？
这是我的sessionInfo：
> sessionInfo()
R version 3.2.3 (2015-12-10)
Platform: x86_64-w64-mingw32/x64 (64-bit)
Running under: Windows >= 8 x64 (build 9200)
locale:
[1] LC_COLLATE=Dutch_Netherlands.1252 LC_CTYPE=Dutch_Netherlands.1252 LC_MONETARY=Dutch_Netherlands.1252
[4] LC_NUMERIC=C LC_TIME=Dutch_Netherlands.1252
attached base packages:
[1] stats graphics grDevices utils datasets methods base
other attached packages:
[1] ggvis_0.4.2 dplyr_0.4.3 ROCR_1.0-7 gplots_3.0.1 FNN_1.1
loaded via a namespace (and not attached):
[1] Rcpp_0.12.4 gtools_3.5.0 digest_0.6.9 assertthat_0.1 mime_0.4
[6] bitops_1.0-6 R6_2.1.2 xtable_1.8-2 DBI_0.3.1 magrittr_1.5
[11] KernSmooth_2.23-15 lazyeval_0.1.10 gdata_2.17.0 tools_3.2.3 shiny_0.13.2
[16] httpuv_1.3.3 parallel_3.2.3 caTools_1.17.1 htmltools_0.3.5