[R] Trying to understand cut

[Jeff Newmiller]

Have you read FAQ 7.31 recently, John? Your whole premise is flawed. You should be thinking of ranges  [0,10), [10,20), and so on because numbers ending in 0.9 are never going to be exact. 
-- 
Sent from my phone. Please excuse my brevity.

On April 16, 2016 7:38:50 PM PDT, John Sorkin <jsorkin at grecc.umaryland.edu> wrote:
>I am trying to understand cut so I can divide a list of numbers into 10
>group:
>  0-9.0
>10-10.9
>20-20.9
>30-30.9,
>40-40.9,
>50-50.9
>60-60.9
>70-70.9
>80-80.9
>90-90.9
> 
>As I try to do this, I have been playing with the cut function.
>Surprising the following for applications of cut give me the exact same
>groups. This surprises me given that I have varied parameters
>include.lowest and right. Can someone help me understand what
>include.lowest and right do? I have looked at the help page, but I
>don't seem to understand what I am being told!
>Thank you,
>John
>
>values <- c((0:99),c(0.9:99.9))
>sort(values)
>c1<-cut(values,10,include.lowest=FALSE,right=TRUE)
>c2<-cut(values,10,include.lowest=FALSE,right=FALSE)
>c3<-cut(values,10,include.lowest=TRUE,right=TRUE)
>c4<-cut(values,10,include.lowest=TRUE,right=FALSE)
>cbind(min=aggregate(values,list(c1),min),max=aggregate(values,list(c1),max))
>cbind(min=aggregate(values,list(c2),min),max=aggregate(values,list(c2),max))
>cbind(min=aggregate(values,list(c3),min),max=aggregate(values,list(c3),max))
>cbind(min=aggregate(values,list(c4),min),max=aggregate(values,list(c4),max))
>
>You can run the code below, or inspect the results I got which are
>reproduced below:
> 
>>
>cbind(min=aggregate(values,list(c1),min),max=aggregate(values,list(c1),max))
>      min.Group.1 min.x    max.Group.1 max.x
>1  (-0.0999,9.91]     0 (-0.0999,9.91]   9.9
>2     (9.91,19.9]    10    (9.91,19.9]  19.9
>3     (19.9,29.9]    20    (19.9,29.9]  29.9
>4     (29.9,39.9]    30    (29.9,39.9]  39.9
>5       (39.9,50]    40      (39.9,50]  49.9
>6         (50,60]    50        (50,60]  59.9
>7         (60,70]    60        (60,70]  69.9
>8         (70,80]    70        (70,80]  79.9
>9         (80,90]    80        (80,90]  89.9
>10       (90,100]    90       (90,100]  99.9
>>
>cbind(min=aggregate(values,list(c2),min),max=aggregate(values,list(c2),max))
>      min.Group.1 min.x    max.Group.1 max.x
>1  [-0.0999,9.91)     0 [-0.0999,9.91)   9.9
>2     [9.91,19.9)    10    [9.91,19.9)  19.9
>3     [19.9,29.9)    20    [19.9,29.9)  29.9
>4     [29.9,39.9)    30    [29.9,39.9)  39.9
>5       [39.9,50)    40      [39.9,50)  49.9
>6         [50,60)    50        [50,60)  59.9
>7         [60,70)    60        [60,70)  69.9
>8         [70,80)    70        [70,80)  79.9
>9         [80,90)    80        [80,90)  89.9
>10       [90,100)    90       [90,100)  99.9
>>
>cbind(min=aggregate(values,list(c3),min),max=aggregate(values,list(c3),max))
>      min.Group.1 min.x    max.Group.1 max.x
>1  [-0.0999,9.91]     0 [-0.0999,9.91]   9.9
>2     (9.91,19.9]    10    (9.91,19.9]  19.9
>3     (19.9,29.9]    20    (19.9,29.9]  29.9
>4     (29.9,39.9]    30    (29.9,39.9]  39.9
>5       (39.9,50]    40      (39.9,50]  49.9
>6         (50,60]    50        (50,60]  59.9
>7         (60,70]    60        (60,70]  69.9
>8         (70,80]    70        (70,80]  79.9
>9         (80,90]    80        (80,90]  89.9
>10       (90,100]    90       (90,100]  99.9
>>
>cbind(min=aggregate(values,list(c4),min),max=aggregate(values,list(c4),max))
>      min.Group.1 min.x    max.Group.1 max.x
>1  [-0.0999,9.91)     0 [-0.0999,9.91)   9.9
>2     [9.91,19.9)    10    [9.91,19.9)  19.9
>3     [19.9,29.9)    20    [19.9,29.9)  29.9
>4     [29.9,39.9)    30    [29.9,39.9)  39.9
>5       [39.9,50)    40      [39.9,50)  49.9
>6         [50,60)    50        [50,60)  59.9
>7         [60,70)    60        [60,70)  69.9
>8         [70,80)    70        [70,80)  79.9
>9         [80,90)    80        [80,90)  89.9
>10       [90,100]    90       [90,100]  99.9
>John David Sorkin M.D., Ph.D.
>Professor of Medicine
>Chief, Biostatistics and Informatics
>University of Maryland School of Medicine Division of Gerontology and
>Geriatric Medicine
>Baltimore VA Medical Center
>10 North Greene Street
>GRECC (BT/18/GR)
>Baltimore, MD 21201-1524
>(Phone) 410-605-7119
>(Fax) 410-605-7913 (Please call phone number above prior to faxing) 
>
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