Downloading files and using the cache

One of the main purposes of mtgr is to obtain data about drafts from 17lands.com. These typically come in the form of rather large, compressed CSV files. mtgr helps you maintain these files by storing them in a folder referred to as the “cache”.

Let’s see how to use this feature.

Location of the cache

library(mtgr)

The location of the cache defaults to a location specific to your OS that is designated for storing files related to this package. You can see where this is located like this:

mr_cache_dir()
#> [1] "/home/runner/.local/share/R/mtgr"

Notice that the exact path will differ based on your computer setup.

You can check the current contents of the cache like so:

list.files(mr_cache_dir())
#> character(0)

Downloading files to the cache

By default, datasets from 17lands will be downloaded to the cache.

Here, let’s download Khans of Tarkir game data for Premier Draft to the cache.

mr_download_17lands_file(set = "KTK", data_type = "game", event_type = "premier")
#> ℹ Starting download
#> ✔ Data downloaded to /home/runner/.local/share/R/mtgr/game_data_public.KTK.PremierDraft.csv.gz
#> /home/runner/.local/share/R/mtgr/game_data_public.KTK.PremierDraft.csv.gz
list.files(mr_cache_dir())
#> [1] "game_data_public.KTK.PremierDraft.csv.gz"

If you prefer to store the files in a folder of your choosing, you can do that with the cache_dir argument:

mr_download_17lands_file(
  set = "KTK", data_type = "game", event_type = "premier",
  cache_dir = tempdir())
#> ℹ Starting download
#> ✔ Data downloaded to /tmp/RtmpGb8OF4/game_data_public.KTK.PremierDraft.csv.gz
#> /tmp/RtmpGb8OF4/game_data_public.KTK.PremierDraft.csv.gz

You can also change the default location of the cache using the mr_cache option:

# (save any existing settings first)
old_cache_setting <- getOption("mr_cache")

# Change location of cache to temporary directory
options(mr_cache = tempdir())
mr_cache_dir()
#> [1] "/tmp/RtmpGb8OF4"

# restore existing settings
options(mr_cache = old_cache_setting)

This way, you don’t have to specify it each time you call a function that uses the cache.

If you want to use this approach, it is recommended to include the call to options() at the top of your script or in your .Rprofile.

Cached files won’t be re-downloaded

The whole point of having a cache is to avoid re-downloading files. So if we run mr_download_17lands_file() for the same dataset again, it will just return the path to the existing file instead of re-downloading it (you should notice the command runs almost instantaneously this time, whereas the first time it took several seconds to download).

mr_download_17lands_file(set = "KTK", data_type = "game", event_type = "premier")
#> /home/runner/.local/share/R/mtgr/game_data_public.KTK.PremierDraft.csv.gz

However, sometimes new data may be available and you do want to re-download. In that case, set overwrite = TRUE to re-download and overwite the existing file:

mr_download_17lands_file(
  set = "KTK", data_type = "game", event_type = "premier",
  overwrite = TRUE)
#> ℹ Existing file detected, deleting
#> ✔ /home/runner/.local/share/R/mtgr/game_data_public.KTK.PremierDraft.csv.gz deleted
#> ℹ Starting download
#> ✔ Data downloaded to /home/runner/.local/share/R/mtgr/game_data_public.KTK.PremierDraft.csv.gz
#> /home/runner/.local/share/R/mtgr/game_data_public.KTK.PremierDraft.csv.gz

The mr_download_17lands_file() function is user-facing, but if your goal is to load the data directly into R (which is most likely the case!), you can skip this function and use mr_get_17lands_data() instead. mr_get_17lands_data() will download the necessary data file for you first, then load it. And of course it will use the cached file if one is available.

ktk <- mr_get_17lands_data(set = "KTK", data_type = "game", event_type = "premier")
#> ℹ Loading data
#> ✔ Data loaded

# The dataset is large, so just print out part of it
dim(ktk)
#> [1] 212170   1290
ktk[1:6, 1:6]
#>    expansion   event_type                         draft_id          draft_time
#>       <char>       <char>                           <char>              <POSc>
#> 1:       KTK PremierDraft e794b242c5bb4570a728c8f05bdc5595 2023-12-12 17:12:56
#> 2:       KTK PremierDraft e794b242c5bb4570a728c8f05bdc5595 2023-12-12 17:12:56
#> 3:       KTK PremierDraft e794b242c5bb4570a728c8f05bdc5595 2023-12-12 17:12:56
#> 4:       KTK PremierDraft e794b242c5bb4570a728c8f05bdc5595 2023-12-12 17:12:56
#> 5:       KTK PremierDraft e794b242c5bb4570a728c8f05bdc5595 2023-12-12 17:12:56
#> 6:       KTK PremierDraft e794b242c5bb4570a728c8f05bdc5595 2023-12-12 17:12:56
#>              game_time build_index
#>                 <POSc>       <int>
#> 1: 2023-12-12 17:42:14           0
#> 2: 2023-12-12 17:46:29           0
#> 3: 2023-12-12 17:53:05           0
#> 4: 2023-12-12 18:05:30           0
#> 5: 2023-12-12 18:10:20           1
#> 6: 2023-12-12 18:12:33           1

Coming soon

I plan to add more functionality to see what is in the cache and clear it out or update the files etc.

Location of the cache

Downloading files to the cache

Cached files won’t be re-downloaded

Files are downloaded automatically when loading into R

Coming soon