我需要安装GitHub上可用的软件包，但是我无法按照开发人员提供的建议步骤安装它。软件包为lodown（https://github.com/ajdamico/lodown），我的R版本为3.5.2。 RStudio是1.1.463。
我尝试使用install_github()函数的标准方法。该指南如下：http://asdfree.com/prerequisites.html。
R询问我要更新哪个软件包，而lodown不在其中。
install.packages("devtools" , repos = "http://cran.rstudio.com/")
library(devtools)
install_github("ajdamico/lodown" , dependencies = TRUE)
该方法应该可以使用，但是在函数install_github()中的第三行失败。
> install_github( "ajdamico/lodown" , dependencies = TRUE )
Downloading GitHub repo ajdamico/lodown@master
These packages have more recent versions available.
Which would you like to update?
1: All 2: CRAN packages only 3: None
4: ellipsis (0.1.0 -> 0.2.0 ) [CRAN] 5: evaluate (0.13 -> 0.14 ) [CRAN] 6: ggplot2 (3.1.1 -> 3.2.0 ) [CRAN]
7: mime (0.6 -> 0.7 ) [CRAN] 8: numDeriv (2016.8-1 -> 2016.8-1.1) [CRAN] 9: openssl (1.3 -> 1.4 ) [CRAN]
10: progress (1.2.0 -> 1.2.2 ) [CRAN] 11: purrr (0.3.0 -> 0.3.2 ) [CRAN] 12: R6 (2.3.0 -> 2.4.0 ) [CRAN]
13: Rcpp (1.0.0 -> 1.0.1 ) [CRAN] 14: RCurl (1.95-4.11 -> 1.95-4.12 ) [CRAN] 15: readxl (1.2.0 -> 1.3.1 ) [CRAN]
16: rlang (0.3.1 -> 0.3.4 ) [CRAN] 17: survey (3.35-1 -> 3.36 ) [CRAN] 18: sys (3.1 -> 3.2 ) [CRAN]
19: tibble (2.0.1 -> 2.1.3 ) [CRAN]
Enter one or more numbers separated by spaces, or an empty line to cancel
1:
Installing 38 packages: digest, gridExtra, gtable, haven, highr, Hmisc, htmlTable, htmltools, htmlwidgets, jpeg, knitr, labeling, latticeExtra, lazyeval, markdown, memisc, mitools, munsell, plyr, R.methodsS3, R.oo, R.utils, RColorBrewer, read.dbc, repr, reshape2, rvest, SAScii, scales, selectr, vctrs, viridis, viridisLite, xfun, XML, xml2, xtable, zeallot
Installing packages into ‘C:/Users/Rik/Documents/R/win-library/3.5’
(as ‘lib’ is unspecified)
trying URL 'https://cran.rstudio.com/bin/windows/contrib/3.5/digest_0.6.19.zip'
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trying URL 'https://cran.rstudio.com/bin/windows/contrib/3.5/knitr_1.23.zip'
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trying URL 'https://cran.rstudio.com/bin/windows/contrib/3.5/labeling_0.3.zip'
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trying URL 'https://cran.rstudio.com/bin/windows/contrib/3.5/latticeExtra_0.6-28.zip'
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trying URL 'https://cran.rstudio.com/bin/windows/contrib/3.5/lazyeval_0.2.2.zip'
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trying URL 'https://cran.rstudio.com/bin/windows/contrib/3.5/markdown_1.0.zip'
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trying URL 'https://cran.rstudio.com/bin/windows/contrib/3.5/memisc_0.99.17.2.zip'
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trying URL 'https://cran.rstudio.com/bin/windows/contrib/3.5/mitools_2.4.zip'
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trying URL 'https://cran.rstudio.com/bin/windows/contrib/3.5/munsell_0.5.0.zip'
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trying URL 'https://cran.rstudio.com/bin/windows/contrib/3.5/plyr_1.8.4.zip'
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package ‘digest’ successfully unpacked and MD5 sums checked
Error: (converted from warning) cannot remove prior installation of package ‘digest’
> library(lodown)
Error in library(lodown) : there is no package called ‘lodown’