Counting the frequency of unique values - R

Question

I am working with the 'mtcars' data-set:

                   mpg cyl disp  hp drat    wt  qsec vs am gear carb
Mazda RX4         21.0   6  160 110 3.90 2.620 16.46  0  1    4    4
Mazda RX4 Wag     21.0   6  160 110 3.90 2.875 17.02  0  1    4    4
Datsun 710        22.8   4  108  93 3.85 2.320 18.61  1  1    4    1
Hornet 4 Drive    21.4   6  258 110 3.08 3.215 19.44  1  0    3    1
Hornet Sportabout 18.7   8  360 175 3.15 3.440 17.02  0  0    3    2
Valiant           18.1   6  225 105 2.76 3.460 20.22  1  0    3    1

I want to find out the number of frequency of unique values for the 'cyl' column, i.e, number of occurences of each value. 

Answer 1

table() function will help you out in this case:

table(mtcars$cyl)

 4  6  8 
11  7 14

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Comments

how to visualize it so that it will that particular element along with it's frequency

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You can use plyr module. It will give you the frequency count. You can see the below example.

> library("plyr")
> count(mtcars, 'gear')
  gear freq
1    3   15
2    4   12
3    5    5

Answer 2

Try this,

lapply(mtcars,function(x){ length(unique(x))})

Answer 3

Hi,

You can use plyr module. It will give you the frequency count. You can see the below example.

> library("plyr")
> count(mtcars, 'gear')
  gear freq
1    3   15
2    4   12
3    5    5