其实本来是备课转录组下游分析，安装一个包，出现了一摞error，最后是一摞整齐的warning。
non-zero exit status是很常见的一个问题，解决办法是到安装路径，安装路径下每个包是一个文件夹，把报错里的包对应的文件夹找出来删掉，重新运行安装代码即可。
之前写过一篇讲这个问题：
mac让你找不到路径
氮素，我最近复盘了我的R语言基础讲义，tidyverse里的stringr包是缺少练习题的，刚好今天这个可以拿来用了。
题目
很简单，从上面截图的warning信息里提取出所有包的名字。
做法
step1：赋值
我们把这段直接复制过来的warning作为一个长字符串，没有问题。对于字符串来说，单双引号没有特别本质的区别，但是当出现嵌套的时候就不行咯，这是第一个坑。
如果用双引号会发现：
一片报错哗啦啦，配色还有点不对劲。
这是因为这个长字符串内部含有双引号。好在没有单引号，所以我们可以给整个字符串两端加单引号，就可以成功赋值。
x='3: In install.packages(update[instlib == l, "Package"], l, repos = repos, :
installation of package ‘BiocParallel’ had non-zero exit status
4: In install.packages(update[instlib == l, "Package"], l, repos = repos, :
installation of package ‘feather’ had non-zero exit status
5: In install.packages(update[instlib == l, "Package"], l, repos = repos, :
installation of package ‘geometry’ had non-zero exit status
6: In install.packages(update[instlib == l, "Package"], l, repos = repos, :
installation of package ‘ggraph’ had non-zero exit status
7: In install.packages(update[instlib == l, "Package"], l, repos = repos, :
installation of package ‘RcppArmadillo’ had non-zero exit status
8: In install.packages(update[instlib == l, "Package"], l, repos = repos, :
installation of package ‘vegan’ had non-zero exit status
9: In install.packages(update[instlib == l, "Package"], l, repos = repos, :
installation of package ‘zip’ had non-zero exit status'
step2：长字符串分割
用空格将整个长字符串分割为单词。
if(!require(stringr))install.packages(stringr)
library(stringr)
str_split(x," ") %>%
unlist() %>%
head(50)
# [1] "3:" "In"
# [3] "install.packages(update[instlib" "=="
# [5] "l," "\"Package\"],"
# [7] "l," "repos"
# [9] "=" "repos,"
# [11] "" ":\n"
# [13] "" "installation"
# [15] "of" "package"
# [17] "‘BiocParallel’" "had"
# [19] "non-zero" "exit"
# [21] "status\n4:" "In"
# [23] "install.packages(update[instlib" "=="
# [25] "l," "\"Package\"],"
# [27] "l," "repos"
# [29] "=" "repos,"
# [31] "" ":\n"
# [33] "" "installation"
# [35] "of" "package"
# [37] "‘feather’" "had"
# [39] "non-zero" "exit"
# [41] "status\n5:" "In"
# [43] "install.packages(update[instlib" "=="
# [45] "l," "\"Package\"],"
# [47] "l," "repos"
# [49] "=" "repos,"
step3：提取包名
所有的包名有个共同点，被两个中文单引号包围，匹配模式可以写成^‘，即以单引号开头。
str_split(x," ") %>%
unlist() %>%
str_subset("^‘")
#[1] "‘BiocParallel’" "‘feather’" "‘geometry’" "‘ggraph’"
#[5] "‘RcppArmadillo’" "‘vegan’" "‘zip’"
强迫症还需要做一件事，就是去掉单引号。
step4：去掉单引号
用到的函数是str_replace_all，因为str_replace默认只替换匹配到的第一个字符。匹配模式[’‘]表示前后单引号都可以，替换为空字符串""就是删除咯。
str_split(x," ") %>%
unlist() %>%
str_subset("^‘") %>%
str_replace_all("[’‘]","")
二路解法
y = x %>%
str_replace_all("’","‘") %>%
str_split("‘") %>%
unlist()
y[str_length(y)<20]
#[1] "BiocParallel" "feather" "geometry" "ggraph" "RcppArmadillo"
#[6] "vegan" "zip"
分隔符只能有一个，如果事实有两个，那就替换一下。
有没有解法三？我正则表达式学艺不精，不会表示"两个引号中间的字符"，但我jio的肯定可以实现，如果你刚好会，不妨告诉我啊。
不定期的放一下我的微信二维码。
