function 的 Output 檢查和安裝缺失的包

Question

為文字牆道歉。

Based on this post and this post , primarily, I wrote a function to let me install a list of packages at the start of every R script, without having to go through the cycle of "Call function -> get error message -> install package “ 每一次。 function 是這樣的：

`packages_installed <- function(pkg_list){
        pkgs <- unlist(pkg_list)
        req <- unlist(lapply(pkgs, require, character.only = TRUE))
        not_installed <- pkgs[req == FALSE]
        lapply(not_installed, install.packages, 
               repos = "http://cran.r-project.org")#also add lib.loc later
        lapply(pkgs, library, character.only = TRUE)
`

但是，當我嘗試運行它時，output 是已安裝的軟件包列表。 例如，這是我的試運行：

```package_list <- c("dagitty","MMWRweek","ggplot2","parallel")```
```packages_installed(package_list)```

這是我的 output：

```
[[1]]
 [1] "dagitty"       "parallel"      "CoxBoost"      "prodlim"      
 [5] "Matrix"        "survival"      "spatstat"      "rpart"        
 [9] "nlme"          "spatstat.data" "ggmap"         "leaflet"      
[13] "spdep"         "spData"        "sp"            "pdftools"     
[17] "data.table"    "forcats"       "stringr"       "dplyr"        
[21] "purrr"         "readr"         "tidyr"         "tibble"       
[25] "tidyverse"     "ggplot2"       "sf"            "RJSONIO"      
[29] "stats"         "graphics"      "grDevices"     "utils"        
[33] "datasets"      "methods"       "base"         

[[2]]
 [1] "MMWRweek"      "dagitty"       "parallel"      "CoxBoost"     
 [5] "prodlim"       "Matrix"        "survival"      "spatstat"     
 [9] "rpart"         "nlme"          "spatstat.data" "ggmap"        
[13] "leaflet"       "spdep"         "spData"        "sp"           
[17] "pdftools"      "data.table"    "forcats"       "stringr"      
[21] "dplyr"         "purrr"         "readr"         "tidyr"        
[25] "tibble"        "tidyverse"     "ggplot2"       "sf"           
[29] "RJSONIO"       "stats"         "graphics"      "grDevices"    
[33] "utils"         "datasets"      "methods"       "base"         

[[3]]
 [1] "MMWRweek"      "dagitty"       "parallel"      "CoxBoost"     
 [5] "prodlim"       "Matrix"        "survival"      "spatstat"     
 [9] "rpart"         "nlme"          "spatstat.data" "ggmap"        
[13] "leaflet"       "spdep"         "spData"        "sp"           
[17] "pdftools"      "data.table"    "forcats"       "stringr"      
[21] "dplyr"         "purrr"         "readr"         "tidyr"        
[25] "tibble"        "tidyverse"     "ggplot2"       "sf"           
[29] "RJSONIO"       "stats"         "graphics"      "grDevices"    
[33] "utils"         "datasets"      "methods"       "base"         

[[4]]
 [1] "MMWRweek"      "dagitty"       "parallel"      "CoxBoost"     
 [5] "prodlim"       "Matrix"        "survival"      "spatstat"     
 [9] "rpart"         "nlme"          "spatstat.data" "ggmap"        
[13] "leaflet"       "spdep"         "spData"        "sp"           
[17] "pdftools"      "data.table"    "forcats"       "stringr"      
[21] "dplyr"         "purrr"         "readr"         "tidyr"        
[25] "tibble"        "tidyverse"     "ggplot2"       "sf"           
[29] "RJSONIO"       "stats"         "graphics"      "grDevices"    
[33] "utils"         "datasets"      "methods"       "base"         

Warning messages:
1: In library(package, lib.loc = lib.loc, character.only = TRUE, logical.return = TRUE,  :
  there is no package called ‘dagitty’
2: In library(package, lib.loc = lib.loc, character.only = TRUE, logical.return = TRUE,  :
  there is no package called ‘MMWRweek’
```

我了解警告消息，它們是來自 function 中的require調用的 output。 這是 output 每次我調用 function，即使 package 已經安裝和加載。 據我所知，這些是全球環境中的包，我不清楚如何防止它們出現。 任何幫助表示贊賞。

Answer 1

necessary_packages <- c("DBI", "odbc")

new_packages <- necessary_packages[!(necessary_packages %in% installed.packages()[,"Package"])]

if(seq_along(new_packages) > 0){install.packages(new_packages, dependencies = TRUE)}

lapply(necessary_packages, require, character.only = TRUE)

Answer 2

一位朋友幫我在library function 的文檔中找到了答案，在問這個問題之前我應該更仔細地閱讀：

“通常庫返回（不可見）附加包的列表，但如果logical.return 為TRUE，則返回TRUE 或FALSE。當調用庫（）時，它返回object 的class “libraryIQR”，對於庫（幫助=），其中之一class “packageInfo”。

因此，我修改了我的 function 只返回它是否已加載。

packages_installed <- function(pkg_list){
    pkgs <- unlist(pkg_list)
    req <- unlist(lapply(pkgs, require, character.only = TRUE, 
                         quietly = TRUE))
    not_installed <- pkgs[req == FALSE]
    lapply(not_installed, install.packages, 
           repos = "http://cran.r-project.org")#also add lib.loc later
    sapply(pkgs, library, character.only = TRUE, 
           logical.return = TRUE, warn.conflicts = TRUE)

}

現在是參數package_list的 output

package_list <- list("rNOMADS","adehabitatMA","raster","rgdal","rgeos"); packages_installed(package_list)

讀作

rNOMADS adehabitatMA raster rgdal rgeos TRUE TRUE TRUE TRUE TRUE