How to find the frequency with subsetting in base R?

R ProgrammingServer Side ProgrammingProgramming

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
raja
Updated on 03-Nov-2021 07:36:30

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