朱莉娅：http.download函数可以创建一个目录，而不是存在吗？

Question

此代码失败是因为../ data/housing/目录不存在：

function FetchHousingData(url::String, path::String)
    println("FetchHousingData " * Dates.format(now(), "HH:MM:SS") )
    HTTP.download(url, path)
    println("done "  * Dates.format(now(), "HH:MM:SS") )
end

housingUrl = "https://raw.githubusercontent.com/ageron/handson-ml2/master/datasets/housing/housing.tgz"
housingPathFile = "../data/housing/housing.tgz"

FetchHousingData(housingUrl, housingPathFile)

有没有办法让http.download（）创建一个缺少的目录？我找不到http.download的文档。

Answer 1

您可以通过输入帮助模式从repper中获取DOCS（在REPP提示下按？）：

help?> HTTP.download
  download(url, [local_path], [headers]; update_period=1, kw...)

  Similar to Base.download this downloads a file, returning the filename. If the local_path:

    •  is not provided, then it is saved in a temporary directory

    •  if part to a directory is provided then it is saved into that directory

    •  otherwise the local path is uses as the filename to save to.

  When saving into a directory, the filename is determined (where possible), from the rules of the HTTP.

    •  update_period controls how often (in seconds) to report the progress.
       • set to Inf to disable reporting

    •  headers specifies headers to be used for the HTTP GET request

    •  any additional keyword args (kw...) are passed on to the HTTP request.

http.http.http.download似乎没有Kwarg要创建目录，但您可能对isdir：

help?> isdir

  isdir(path) -> Bool

  Return true if path is a directory, false otherwise.

  Examples
  ≡≡≡≡≡≡≡≡≡≡

  julia> isdir(homedir())
  true
  
  julia> isdir("not/a/directory")
  false

  See also isfile and ispath.

mkdir：

help?> mkdir

  mkdir(path::AbstractString; mode::Unsigned = 0o777)

  Make a new directory with name path and permissions mode. mode defaults to 0o777, modified by the current file creation mask. This function never creates more than one directory. If the directory already exists, or some intermediate
  directories do not exist, this function throws an error. See mkpath for a function which creates all required intermediate directories. Return path.

  Examples
  ≡≡≡≡≡≡≡≡≡≡

  julia> mkdir("testingdir")
  "testingdir"
  
  julia> cd("testingdir")
  
  julia> pwd()
  "/home/JuliaUser/testingdir"

Answer 2

我更喜欢使用mkPath（在NILS显示的文档中也提到），因为它会创建父目录，并且如果目录已经存在，则不会产生错误：

housingPathFile = "../data/housing/housing.tgz"
mkpath(dirname(housingPathFile))