r - R中所有CRAN中所有软件包的列表和描述

Question

我可以使用以下功能获取所有可用软件包的列表:

ap <- available.packages()

但是如何从R中获得这些软件包的描述，因此我可以得到一个带有两列的data.frame:包裹和描述？

Answer 1

我实际上认为您希望将“包”和“标题”作为“描述”运行到几行。所以这是前者，如果您确实想要“Description”，只需将“Description”放在最后一个子集中:

R> ## from http://developer.r-project.org/CRAN/Scripts/depends.R and adapted
R>
R> require("tools")
R>
R> getPackagesWithTitle <- function() {
+     contrib.url(getOption("repos")["CRAN"], "source") 
+     description <- sprintf("%s/web/packages/packages.rds", 
+                            getOption("repos")["CRAN"])
+     con <- if(substring(description, 1L, 7L) == "file://") {
+         file(description, "rb")
+     } else {
+         url(description, "rb")
+     }
+     on.exit(close(con))
+     db <- readRDS(gzcon(con))
+     rownames(db) <- NULL
+
+     db[, c("Package", "Title")]
+ }
R>
R>
R> head(getPackagesWithTitle())               # I shortened one Title here...
     Package              Title
[1,] "abc"                "Tools for Approximate Bayesian Computation (ABC)"
[2,] "abcdeFBA"           "ABCDE_FBA: A-Biologist-Can-Do-Everything of Flux ..."
[3,] "abd"                "The Analysis of Biological Data"
[4,] "abind"              "Combine multi-dimensional arrays"
[5,] "abn"                "Data Modelling with Additive Bayesian Networks"
[6,] "AcceptanceSampling" "Creation and evaluation of Acceptance Sampling Plans"
R>