R c.Date() 引发警告 Calling 'structure(NULL, *)' is deprecated [英] R c.Date() raises warning Calling 'structure(NULL, *)' is deprecated

问题描述

我注意到调用 c.Date() 来初始化一个空的日期向量会引发警告.我使用的是 R 版本 3.4.0.

警告信息是:

<块引用>

警告信息:在结构中(c(unlist(lapply(list(...), unclass))),class = "Date") :不推荐调用结构(NULL，*)"，因为NULL 不能有属性.考虑'结构(列表()，*)'相反.

有人解释一下吗?如何在没有此警告的情况下初始化空的 DATE 向量?

可重现的代码:

vect = c.Date()d = as.Date("31/12/2018", format = "%d/%m/%Y")for(i 在 1:10){vect = c(vect, d)d = d+1}打印(矢量)

结果是

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[1] "2016-03-31" "2016-04-01" "2016-04-02" "2016-04-03" [5]"2016-04-04" "2016-04-05" "2016-04-06" "2016-04-07" [9] "2016-04-08"2016-04-09"

如果我不使用 c.Date() 而是使用 c().

vect = c()d = as.Date("31/12/2018", format = "%d/%m/%Y")for(i 在 1:10){vect = c(vect, d)d = d+1}打印(矢量)

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[1] 17896 17897 17898 17899 17900 17901 17902 17903 17904 17905

这是不可取的.

解决方案

r2evans 回答了我的问题.Sys.Date()[0]诀窍.

我在这里发帖是为了将其标记为已解决，以供将来的读者使用.

I noticed that calling c.Date() to initialize an empty date vector raises a Warning. I am on R version 3.4.0.

The warning message is :

Warning message: In structure(c(unlist(lapply(list(...), unclass))), class = "Date") : Calling 'structure(NULL, *)' is deprecated, as NULL cannot have attributes. Consider 'structure(list(), *)' instead.

Do anyone has an explantion? How to initialize an empty DATE vector without having this warning?

A reproducible code :

vect = c.Date()
d = as.Date("31/12/2018", format = "%d/%m/%Y")
for(i in 1:10){
    vect = c(vect, d)
    d = d+1
}
print(vect)

Result is

[1] "2016-03-31" "2016-04-01" "2016-04-02" "2016-04-03" [5] "2016-04-04" "2016-04-05" "2016-04-06" "2016-04-07" [9] "2016-04-08" "2016-04-09"

If I don't use c.Date() but c() instead.

vect = c()

d = as.Date("31/12/2018", format = "%d/%m/%Y")
for(i in 1:10){
  vect = c(vect, d)
  d = d+1
}

print(vect)

[1] 17896 17897 17898 17899 17900 17901 17902 17903 17904 17905

which is undesirable.

解决方案

r2evans answerd my question. Sys.Date()[0] does the trick.

I post here to mark it as resolved for future readers.

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