我正在尝试修改R中的cit <- citation("ggplot2")
cit$textVersion
#[1] "H. Wickham. ggplot2: Elegant Graphics for Data Analysis. Springer-Verlag New York, 2009."
cit$textVersion <- "Hadley Wickham and Winston Chang (2016). ggplot2: Create Elegant Data Visualisations Using
the Grammar of Graphics. R package version 2.2.1."
对象，如下所示
cit$textVersion
#[1] "H. Wickham. ggplot2: Elegant Graphics for Data Analysis. Springer-Verlag New York, 2009."
但没有变化。
cit如果我们检查textVersion的结构，现在有两个textVersion属性。如何单独修改原始str(cit)
List of 1
$ :Class 'bibentry' hidden list of 1
..$ :List of 6
.. ..$ author :Class 'person' hidden list of 1
.. .. ..$ :List of 5
.. .. .. ..$ given : chr "Hadley"
.. .. .. ..$ family : chr "Wickham"
.. .. .. ..$ role : NULL
.. .. .. ..$ email : NULL
.. .. .. ..$ comment: NULL
.. ..$ title : chr "ggplot2: Elegant Graphics for Data Analysis"
.. ..$ publisher: chr "Springer-Verlag New York"
.. ..$ year : chr "2009"
.. ..$ isbn : chr "978-0-387-98140-6"
.. ..$ url : chr "http://ggplot2.org"
.. ..- attr(*, "bibtype")= chr "Book"
.. ..- attr(*, "textVersion")= chr "H. Wickham. ggplot2: Elegant Graphics for Data Analysis. Springer-Verlag New York, 2009."
.. ..- attr(*, "textversion")= chr "Hadley Wickham and Winston Chang (2016). ggplot2: Create Elegant Data Visualisations Using\n the Grammar of Gr"| __truncated__
- attr(*, "mheader")= chr "To cite ggplot2 in publications, please use:"
- attr(*, "class")= chr "bibentry"
？
MySQL答案 0 :(得分：2)
不会修改citation个对象。子集运算符（$，[，还有$<-）是特定的，不允许轻松修改。这是有原因的：citation信息写在包的特定文件中，并且不被认为是被修改的。
我不知道你为什么要这样做，但如果你真的需要，这里有点破解。
#store the class of the object, so can be reassigned later
oc<-class(cit)
#unclass the object to be free to modify
tmp<-unclass(cit)
#assign the new "textVersion"
attr(tmp[[1]],"textVersion")<-"Hadley Wickham and Winston Chang (2016). ggplot2: Create Elegant Data Visualisations Using the Grammar of Graphics. R package version 2.2.1."
#assign the class back
class(tmp)<-oc
tmp
#To cite ggplot2 in publications, please use:
#
# Hadley Wickham and Winston Chang (2016). ggplot2: Create Elegant Data
# Visualisations Using the Grammar of Graphics. R package version
# 2.2.1.
#
#A BibTeX entry for LaTeX users is
#
# @Book{,
# author = {Hadley Wickham},
# title = {ggplot2: Elegant Graphics for Data Analysis},
# publisher = {Springer-Verlag New York},
# year = {2009},
# isbn = {978-0-387-98140-6},
# url = {http://ggplot2.org},
# }