Names missing from table() when called on a certain data.frame() with columnnames

Question

Missing column-names from table()-output

The function table() will print the column-names of the dataframe in the table, when the data.frame() is created like this:

table(data.frame( var1 = "yes", var2 = "no") )
     var2
var1  no
  yes  1

But when i create the data.frame() like this, the table()-function will not print any column names:

e1 <- data.frame( smoking = "no", cvd = "no" ) 
e1 <- e1[rep(1,3495),]
e2 <- data.frame( smoking = "no", cvd = "yes" ) 
e2 <- e2[rep(1,57), ] 
e3 <- data.frame( smoking = "yes",cvd = "no")
e3 <- e3[rep(1,2112),]
e4 <- data.frame( smoking = "yes",cvd = "yes")
e4 <- e4[rep(1,75),]
ee <- rbind( e1,e2,e3,e4)

No names are printed in the table:

> table( ee$smoking, ee$cvd)

        no  yes
  no  3495   57
  yes 2112   75

Despite the ee is actually a data.frame and has names:

> class(ee)
[1] "data.frame"
> names(ee)
[1] "smoking" "cvd"

So my question is why does the table()-function not print names when called on the ee-data.frame?

ab90hi · Accepted Answer · 2017-01-26 08:52:39Z

1

It does print the names if you call table with the data.frame, the below code works:

table(ee)
       cvd
smoking   no  yes
    no  3495   57
    yes 2112   75

But when you call table(ee$cvd,ee$smoking) it treats them as individual vectors and not a data.frame

answered Jan 26, 2017 at 8:52

ab90hi

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akrun · Accepted Answer · 2017-01-26 10:14:00Z

0

There is a dnn argument in table which could work in cases where the input argument are vectors

table(ee$cvd, ee$smoking, dnn = list("smoking", "cvd"))
#       cvd
#smoking   no  yes
#    no  3495 2112
#   yes   57   75

answered Jan 26, 2017 at 10:14

akrun

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