Create a disk.frame containing only specified columns #337

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1. xiaodaigh commented on May 3, 2021

   

   xiaodaigh

   on May 3, 2021

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   You can already do that since {disk.frame} uses {data.table}'s fread which provides the select= option

   library(disk.frame)
   #setup_disk.frame() # omitted since the data is tiny
   
   # write the iris dataset to csv
   data.table::fwrite(iris, "iris.csv")
   
   # read only the Species and Sepal.Length columns via `select = `
   iris.df = disk.frame::csv_to_disk.frame("iris.csv", select = c("Species", "Sepal.Length"))
   
   
   collect(iris.df)
   
   # Species Sepal.Length
   # 1:    setosa          5.1
   # 2:    setosa          4.9
   # 3:    setosa          4.7
   # 4:    setosa          4.6
   # 5:    setosa          5.0
   # ---                       
   #   146: virginica          6.7
   # 147: virginica          6.3
   # 148: virginica          6.5
   # 149: virginica          6.2
   # 150: virginica          5.9
   
2. xiaodaigh

   closed this as completedon May 3, 2021
3. DiskFrame

   locked and limited conversation to collaborators on May 3, 2021