How to make randomly sampled training sets of proportionately equal sizes?










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I want to make a series of randomly sampled training sets that are exactly 75% the size of the full data set. The code below is an example of what I want to achieve except I always want 75 samples of 1, and 25 samples of 2; this code only gives me samples which are close to those sizes but not exact.



column <- c(rep("A", 40), rep("B", 60))
data <- as.data.frame(column)
index <- sample(2,100, replace=TRUE, prob=c(0.75,0.25))


I want to be able to achieve this kind of partitioning without the use of additional packages and just with the base R if possible. Packages don't seem to work for me the vast majority of the time, which is why I have found it difficult to find a solution already.










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    1














    I want to make a series of randomly sampled training sets that are exactly 75% the size of the full data set. The code below is an example of what I want to achieve except I always want 75 samples of 1, and 25 samples of 2; this code only gives me samples which are close to those sizes but not exact.



    column <- c(rep("A", 40), rep("B", 60))
    data <- as.data.frame(column)
    index <- sample(2,100, replace=TRUE, prob=c(0.75,0.25))


    I want to be able to achieve this kind of partitioning without the use of additional packages and just with the base R if possible. Packages don't seem to work for me the vast majority of the time, which is why I have found it difficult to find a solution already.










    share|improve this question
























      1












      1








      1







      I want to make a series of randomly sampled training sets that are exactly 75% the size of the full data set. The code below is an example of what I want to achieve except I always want 75 samples of 1, and 25 samples of 2; this code only gives me samples which are close to those sizes but not exact.



      column <- c(rep("A", 40), rep("B", 60))
      data <- as.data.frame(column)
      index <- sample(2,100, replace=TRUE, prob=c(0.75,0.25))


      I want to be able to achieve this kind of partitioning without the use of additional packages and just with the base R if possible. Packages don't seem to work for me the vast majority of the time, which is why I have found it difficult to find a solution already.










      share|improve this question













      I want to make a series of randomly sampled training sets that are exactly 75% the size of the full data set. The code below is an example of what I want to achieve except I always want 75 samples of 1, and 25 samples of 2; this code only gives me samples which are close to those sizes but not exact.



      column <- c(rep("A", 40), rep("B", 60))
      data <- as.data.frame(column)
      index <- sample(2,100, replace=TRUE, prob=c(0.75,0.25))


      I want to be able to achieve this kind of partitioning without the use of additional packages and just with the base R if possible. Packages don't seem to work for me the vast majority of the time, which is why I have found it difficult to find a solution already.







      r






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      asked Nov 12 '18 at 18:09









      Ryan Tandy

      103




      103






















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          That's how sample is intended to work. You may instead consider two steps:



          idxTrain <- sample(100, 75)
          head(idxTrain)
          # [1] 54 70 3 42 72 67
          length(idxTrain)
          # [1] 75
          idxTest <- setdiff(1:100, idxTrain)
          head(idxTest)
          # [1] 5 7 13 14 19 24
          length(idxTest)
          # [1] 25





          share|improve this answer




















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            1 Answer
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            active

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            1














            That's how sample is intended to work. You may instead consider two steps:



            idxTrain <- sample(100, 75)
            head(idxTrain)
            # [1] 54 70 3 42 72 67
            length(idxTrain)
            # [1] 75
            idxTest <- setdiff(1:100, idxTrain)
            head(idxTest)
            # [1] 5 7 13 14 19 24
            length(idxTest)
            # [1] 25





            share|improve this answer

























              1














              That's how sample is intended to work. You may instead consider two steps:



              idxTrain <- sample(100, 75)
              head(idxTrain)
              # [1] 54 70 3 42 72 67
              length(idxTrain)
              # [1] 75
              idxTest <- setdiff(1:100, idxTrain)
              head(idxTest)
              # [1] 5 7 13 14 19 24
              length(idxTest)
              # [1] 25





              share|improve this answer























                1












                1








                1






                That's how sample is intended to work. You may instead consider two steps:



                idxTrain <- sample(100, 75)
                head(idxTrain)
                # [1] 54 70 3 42 72 67
                length(idxTrain)
                # [1] 75
                idxTest <- setdiff(1:100, idxTrain)
                head(idxTest)
                # [1] 5 7 13 14 19 24
                length(idxTest)
                # [1] 25





                share|improve this answer












                That's how sample is intended to work. You may instead consider two steps:



                idxTrain <- sample(100, 75)
                head(idxTrain)
                # [1] 54 70 3 42 72 67
                length(idxTrain)
                # [1] 75
                idxTest <- setdiff(1:100, idxTrain)
                head(idxTest)
                # [1] 5 7 13 14 19 24
                length(idxTest)
                # [1] 25






                share|improve this answer












                share|improve this answer



                share|improve this answer










                answered Nov 12 '18 at 18:16









                Julius Vainora

                32.4k75979




                32.4k75979



























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