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How to find the frequency with subsetting in base R?
The easiest way to find the frequency is to create a table for the provided vector or data frame column and it can be done with table function. But, if the frequency needs to be found with subsetting then subset function and transform function will also be required as shown in the below examples.
Example 1
Following snippet creates a sample data frame −
head(ChickWeight,20)
Output
The following dataframe is created −
weight Time Chick Diet 1 42 0 1 1 2 51 2 1 1 3 59 4 1 1 4 64 6 1 1 5 76 8 1 1 6 93 10 1 1 7 106 12 1 1 8 125 14 1 1 9 149 16 1 1 10 171 18 1 1 11 199 20 1 1 12 205 21 1 1 13 40 0 2 1 14 49 2 2 1 15 58 4 2 1 16 72 6 2 1 17 84 8 2 1 18 103 10 2 1 19 122 12 2 1 20 138 14 2 1
To find the frequency with subsetting in base R, add the following code to the above snippet −
str(ChickWeight)
Output
If you execute all the above given snippets as a single program, it generates the following Output −
Classes ‘nfnGroupedData’, ‘nfGroupedData’, ‘groupedData’ and 'data.frame': 578 obs. of 4 variables: $ weight: num 42 51 59 64 76 93 106 125 149 171 ... $ Time : num 0 2 4 6 8 10 12 14 16 18 ... $ Chick : Ord.factor w/ 50 levels "18"<"16"<"15"<..: 15 15 15 15 15 15 15 15 15 15 ... $ Diet : Factor w/ 4 levels "1","2","3","4": 1 1 1 1 1 1 1 1 1 1 ... - attr(*, "formula")=Class 'formula' language weight ~ Time | Chick .. ..- attr(*, ".Environment")=<environment: R_EmptyEnv> - attr(*, "outer")=Class 'formula' language ~Diet .. ..- attr(*, ".Environment")=<environment: R_EmptyEnv> - attr(*, "labels")=List of 2 ..$ x: chr "Time" ..$ y: chr "Body weight" - attr(*, "units")=List of 2 ..$ x: chr "(days)" ..$ y: chr "(gm)"
To find the frequency with subsetting in base R, add the following code to the above snippet −
transform(table(Diet=subset(ChickWeight,Time>20,select=Diet)))
Output
If you execute all the above given snippets as a single program, it generates the following Output −
Diet Freq 1 1 16 2 2 10 3 3 10 4 4 9
Example 2
Following snippet creates a sample data frame −
head(mtcars,20)
The following dataframe is created −
mpg cyl disp hp drat wt qsec vs am gear carb Mazda RX4 21.0 6 160.0 110 3.90 2.620 16.46 0 1 4 4 Mazda RX4 Wag 21.0 6 160.0 110 3.90 2.875 17.02 0 1 4 4 Datsun 710 22.8 4 108.0 93 3.85 2.320 18.61 1 1 4 1 Hornet 4 Drive 21.4 6 258.0 110 3.08 3.215 19.44 1 0 3 1 Hornet Sportabout 18.7 8 360.0 175 3.15 3.440 17.02 0 0 3 2 Valiant 18.1 6 225.0 105 2.76 3.460 20.22 1 0 3 1 Duster 360 14.3 8 360.0 245 3.21 3.570 15.84 0 0 3 4 Merc 240D 24.4 4 146.7 62 3.69 3.190 20.00 1 0 4 2 Merc 230 22.8 4 140.8 95 3.92 3.150 22.90 1 0 4 2 Merc 280 19.2 6 167.6 123 3.92 3.440 18.30 1 0 4 4 Merc 280C 17.8 6 167.6 123 3.92 3.440 18.90 1 0 4 4 Merc 450SE 16.4 8 275.8 180 3.07 4.070 17.40 0 0 3 3 Merc 450SL 17.3 8 275.8 180 3.07 3.730 17.60 0 0 3 3 Merc 450SLC 15.2 8 275.8 180 3.07 3.780 18.00 0 0 3 3 Cadillac Fleetwood 10.4 8 472.0 205 2.93 5.250 17.98 0 0 3 4 Lincoln Continental 10.4 8 460.0 215 3.00 5.424 17.82 0 0 3 4 Chrysler Imperial 14.7 8 440.0 230 3.23 5.345 17.42 0 0 3 4 Fiat 128 32.4 4 78.7 66 4.08 2.200 19.47 1 1 4 1 Honda Civic 30.4 4 75.7 52 4.93 1.615 18.52 1 1 4 2 Toyota Corolla 33.9 4 71.1 65 4.22 1.835 19.90 1 1 4 1
To find the frequency with subsetting in base R, add the following code to the above snippet −
str(mtcars)
Output
If you execute all the above given snippets as a single program, it generates the following Output −
'data.frame': 32 obs. of 11 variables: $ mpg : num 21 21 22.8 21.4 18.7 18.1 14.3 24.4 22.8 19.2 ... $ cyl : num 6 6 4 6 8 6 8 4 4 6 ... $ disp: num 160 160 108 258 360 ... $ hp : num 110 110 93 110 175 105 245 62 95 123 ... $ drat: num 3.9 3.9 3.85 3.08 3.15 2.76 3.21 3.69 3.92 3.92 ... $ wt : num 2.62 2.88 2.32 3.21 3.44 ... $ qsec: num 16.5 17 18.6 19.4 17 ... $ vs : num 0 0 1 1 0 1 0 1 1 1 ... $ am : num 1 1 1 0 0 0 0 0 0 0 ... $ gear: num 4 4 4 3 3 3 3 4 4 4 ... $ carb: num 4 4 1 1 2 1 4 2 2 4 ...
To find the frequency with subsetting in base R, add the following code to the above snippet −
transform(table(cyl=subset(mtcars,hp>110,select=cyl)))
Output
If you execute all the above given snippets as a single program, it generates the following Output −
cyl Freq 1 4 1 2 6 3 3 8 14
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