make group (aggregate) data set in R

Suppose you have a data set called sort2013

And you want to calculate the group/aggregate of each Head_age

> sort2013

  Head_age P2_age P3_age P4_age P5_age P6_age P7_age P8_age

1       84     75      0      0      0      0      0      0

2       84     75      0      0      0      0      0      0

3       84     75      0      0      0      0      0      0

4       84     75      0      0      0      0      0      0

5       84     75      0      0      0      0      0      0

6       85     76      0      0      0      0      0      0

Etc...

Do the aggregate or grouping the data frame with aggregate()

> group2013 = aggregate(. ~ Head_age, sort2013, mean)

#aggregate or group of .(all column) ~(by) Head_age, in sort2013 data frame, and calculate the mean of all column. Then input into group2013 data frame

The result would be

> group2013

  Head_age   P2_age   P3_age   P4_age P5_age P6_age P7_age P8_age

1       16  0.00000 0.000000 0.000000      0      0      0      0

2       17  5.00000 0.000000 0.000000      0      0      0      0

3       18 13.44444 0.000000 0.000000      0      0      0      0

4       19 22.38095 7.000000 0.000000      0      0      0      0

5       20 17.45455 0.000000 0.000000      0      0      0      0

6       21 42.60000 6.666667 8.466667      0      0      0      0

Etc...

The result would be automatically sorted as you can see above

sort data in each row in R data set

Suppose we have this kind of data A

And want to sort from the maximum until the minimum value each row

> A

    [1]      [2]          [3]          [4]

[1] 3       7             9              5

[2] 7       9            11             3

[3] 5       3            7               8

We want to sort A by row and resulting like this

    [1]      [2]          [3]          [4]

[1] 3       5             7             9

[2] 3       7             9            11

Etc....

We can sort by row by doing this

>Asorted = t(apply(A,1,sort))  

#sort the data A each row and input to Asorted data

apply(A,1,sort) means apply for A data set, in 1 (row), and sort them
*1: row, 2: column and (1:2): both of row and column

Yet it will be like this. It will be sorted from the minimum value to the maximum value in each row  (reverse)

    [1]      [2]          [3]          [4]

[1] 3       5             7             9

[2] 3       7             9            11

Etc....

What we need to do next is just reverse it by this command

>Asorted = Asorted[ ,ncol(Asorted):1]    

#reverse sequence in column index, and input it (rewrite) to Asorted data

There you go, the result would be like this

>Asorted

    [1]      [2]          [3]          [4]

[1] 9       7             5            3

[2] 11     9             7            3

Etc....