Usage for end-users

The main goal of DataDeps.jl is to simplify life for the user. They should just forget about the data their package needs.

Moving Data

Moving data is a great idea. DataDeps.jl is in favour of moving data. When data is automatically downloaded it will almost always go to the same location: the first (existent, writable) directory on your DATADEPS_LOAD_PATH. Which by-default is DataDeps's scratch space under ~/.julia/scratchspaces/124859b0-ceae-595e-8997-d05f6a7a8dfe/datadeps, such that Pkg.gc() can automatically delete data if DataDeps is uninstalled. But you can move them from there to anywhere in the DATADEPS_LOAD_PATH. (See below)

If you have a large chunk of data that everyone in your lab is using (e.g. a 1TB video corpora), you probably want to shift it to a shared area, like /usr/share/datadeps. Even if you don't have write permissions, you can have a sysadmin move it, and so long as you still have read permission DataDeps.jl will find it and use it for you.

The Load Path

The Load Path is the list of paths that DataDeps.jl looks in when trying to resolve a data dependency. If it doesn't find the data in any of them it will download the data.

It has 3 sources:

  • the package load path:
    • determined from the package where the datadep"NAME" was used
  • the user defined load path
    • determined from the contents of the environment variable DATADEPS_LOAD_PATH
    • this can be a colon separated list (Like most unix path variables)
  • the standard load path
    • depends on your system and configuration
    • normally starts with user specific locations like your home directory, and expands out to shared locations
    • see below lists of examples
    • This can be disabled by setting the DATADEPS_NO_STANDARD_LOAD_PATH environment variable.

In general it should by default include just about anywhere you might want to put the data. If it doesn't, please file an issue. (Unless your location is super-specific, e.g. /MyUniName/student/commons/datadeps). As mentioned you can add things to the load path by setting the environment variable DATADEPS_LOAD_PATH. You can also make symlinks from the locations on the load path to other locations where the data really is, if you'd rather do that.

When loading data the load path is searched in order for a readable folder. When saving data it is searched in order, skipping the package load path, for a writable directory. Simple way to avoid part of the standard load path being used for saving is to delete it, or make it unwritable. You can (and should when desired) move things around between any folder in the load path without redownloading.

Unix Standard Load Path

For the user oxinabox


Windows Standard Load Path

For the user oxinabox, when using JuliaPro, on windows 7. (Other configurations should be fairly similar).


Having multiple copies of the same DataDir

You probably don't want to have multiple copies of a DataDir with the same name. DataDeps.jl will try to handle it as gracefully as it can. But having different DataDeps under the same name, is probably going to lead to packages loading the wrong one. Except if they are (both) located in their packages deps/data folder.

By moving a package's data dependency into its package directory under deps/data, it becomes invisible except to that package. For example ~/.julia/v0.6/EXAMPLEPKG/deps/data/EXAMPLEDATADEP/, for the package EXAMPLEPKG, and the datadep EXAMPLEDATADEP.

Ideally though you should probably raise an issue with the package maintainers and see if one (or both) of them want to change the DataDep name.

Note also when it comes to file level loading, e.g. datadep"Name/subfolder/file.txt", DataDeps.jl does not check all folders with that Name (if you have multiples). If the file is not in the first folder it finds you will be presented with the recovery dialog, from which the easiest option is to select to delete the folder and retry, since that will result in it checking the second folder (as the first one does not exist).

Removing data

Sometimes you don't need the data anymore. You can remove files from within Julia using the rm command. If you had registered a DataDep called MyDataName, then you can remove it with

rm(datadep"MyDataName"; recursive=true)


Currently configuration is done via Environment Variables. It is likely to stay that way, as they are also easy to setup in CI tools. You can set these in the startup.jl file using the ENV dictionary if you don't want to mess up your .profile. However, most people shouldn't need to. DataDeps.jl tries to have very sensible defaults.

  • DATADEPS_ALWAYS_ACCEPT – bypasses the confirmation before downloading data. Set to true (or similar string)
    • default: false
    • Note that it remains your responsibility to understand and read any terms of the data use (this is remains true even if you don't turn on this bypass)
    • This is provided for scripting (in particular CI) use
    • If the CI environment variable is set to true, DATADEPS_ALWAYS_ACCEPTmust be set to true or false. This is to prevent hanging in CI.
  • DATADEPS_PROGRESS_UPDATE_PERIOD – how often (in seconds) to print the progress to the log for the download
    • This is used by the default fetch_method and when implementing custom methods it is good to respect it.
    • default: 5 (seconds) usually; Inf (i.e. no updates) if DATADEPS_ALWAYS_ACCEPT is set.
  • DATADEPS_LOAD_PATH – The list of paths to be prepended to the standard load path to save and load data from
  • DATADEPS_NO_STANDARD_LOAD_PATH if this is set to true (default false), then the aforementioned list of standard load path files is not included
  • DATADEPS_DISABLE_DOWNLOAD – causes any action that would result in the download being triggered to throw an exception.
    • useful e.g. if you are in an environment with metered data, where your datasets should have already been downloaded earlier, and if there were not you want to respond to the situation rather than let DataDeps.jl download them for you.
    • default false
  • DATADEPS_DISABLE_ERROR_CLEANUP – By default DataDeps.jl will cleanup the directory the datadep was being downloaded to if there is an error during the resolution (In any of the fetch, checksum, or post_fetch). For debugging purposes you may wish to disable this cleanup step so you can interrogate the files by hand.