时间戳

首页 > 解决方案 > 获取数据集 R 包中所有对象名称的列表？

r - 获取数据集 R 包中所有对象名称的列表？

问题描述

如何获取数据集包中对象的确切名称列表？

我在这里找到了很多：

data_package = data(package="datasets")
datasets <- as.data.frame(data_package[[3]])$Item
datasets

#   [1] "AirPassengers"          "BJsales"                "BJsales.lead (BJsales)" "BOD"                    "CO2"                    "ChickWeight"           
#   [7] "DNase"                  "EuStockMarkets"         "Formaldehyde"           "HairEyeColor"           "Harman23.cor"           "Harman74.cor"          
#  [13] "Indometh"               "InsectSprays"           "JohnsonJohnson"         "LakeHuron"              "LifeCycleSavings"       "Loblolly"              
#  [19] "Nile"                   "Orange"                 "OrchardSprays"          "PlantGrowth"            "Puromycin"              "Seatbelts"             
#  [25] "Theoph"                 "Titanic"                "ToothGrowth"            "UCBAdmissions"          "UKDriverDeaths"         "UKgas"                 
#  [31] "USAccDeaths"            "USArrests"              "USJudgeRatings"         "USPersonalExpenditure"  "UScitiesD"              "VADeaths"              
#  [37] "WWWusage"               "WorldPhones"            "ability.cov"            "airmiles"               "airquality"             "anscombe"              
#  [43] "attenu"                 "attitude"               "austres"                "beaver1 (beavers)"      "beaver2 (beavers)"      "cars"                  
#  [49] "chickwts"               "co2"                    "crimtab"                "discoveries"            "esoph"                  "euro"                  
#  [55] "euro.cross (euro)"      "eurodist"               "faithful"               "fdeaths (UKLungDeaths)" "freeny"                 "freeny.x (freeny)"     
#  [61] "freeny.y (freeny)"      "infert"                 "iris"                   "iris3"                  "islands"                "ldeaths (UKLungDeaths)"
#  [67] "lh"                     "longley"                "lynx"                   "mdeaths (UKLungDeaths)" "morley"                 "mtcars"                
#  [73] "nhtemp"                 "nottem"                 "npk"                    "occupationalStatus"     "precip"                 "presidents"            
#  [79] "pressure"               "quakes"                 "randu"                  "rivers"                 "rock"                   "sleep"                 
#  [85] "stack.loss (stackloss)" "stack.x (stackloss)"    "stackloss"              "state.abb (state)"      "state.area (state)"     "state.center (state)"  
#  [91] "state.division (state)" "state.name (state)"     "state.region (state)"   "state.x77 (state)"      "sunspot.month"          "sunspot.year"          
#  [97] "sunspots"               "swiss"                  "treering"               "trees"                  "uspop"                  "volcano"               
# [103] "warpbreaks"             "women"

所以像这样的东西会遍历每一个

for(i in 1:length(datasets)) {
  print(get(datasets[i]))
  cat("\n\n")
}

它适用于前两个数据集（AirPassengers和BJsales），但它失败了，BJsales.lead (BJsales)因为它应该被称为datasets::BJsales.lead.

我想我可以使用字符串拆分或类似的方法来丢弃从空格开始的任何内容，但我想知道有没有更简洁的方法来获取dataset包中所有对象的列表？

笔记

ls(getNamespace("datasets"), all.names=TRUE)
# [1] ".__NAMESPACE__."      ".__S3MethodsTable__." ".packageName"

标签： r

解决方案

?data帮助页面上有一条注释说明

如果数据集的名称与应该用于检索它们的参数的名称不同，则索引将有一个类似的条目beaver1 (beavers)，告诉我们beaver1可以通过调用来检索数据集data(beavers)。

所以实际的对象名称是最后括号之前的东西。由于该值仅作为字符串返回，因此不幸的是，您需要将其删除。但你可以做到这一点gsub

datanames <- data(package="datasets")$results[,"Item"]
objnames <- gsub("\\s+\\(.*\\)","", datanames)

for(ds in objnames) {
  print(get(ds))
  cat("\n\n")
}

推荐阅读