[R] Sorting data.frame and again sorting within data.frame

[arun]

library(plyr)
arrange(df,names,desc(dates))
#  names     dates values
#1     A 4/15/2013     31
#2     A 4/14/2013    102
#3     A 4/13/2013     31
#4     B 4/15/2013     34
#5     B 4/14/2013     47
#6     B 4/13/2013     17
#7     C 4/15/2013     10
#8     C 4/14/2013     29
#9     C 4/13/2013     11
#or
df[with(df,order(names,desc(dates))),]
#  names     dates values
#3     A 4/15/2013     31
#7     A 4/14/2013    102
#2     A 4/13/2013     31
#6     B 4/15/2013     34
#8     B 4/14/2013     47
#4     B 4/13/2013     17
#1     C 4/15/2013     10
#9     C 4/14/2013     29
#5     C 4/13/2013     11
A.K.



----- Original Message -----
From: Katherine Gobin <katherine_gobin at yahoo.com>
To: r-help at r-project.org
Cc: 
Sent: Monday, April 15, 2013 2:01 AM
Subject: [R] Sorting data.frame and again sorting within data.frame

Dear R forum,

I have a data.frame as defied below - 

df = data.frame(names = c("C", "A", "A", "B", "C", "B", "A", "B", "C"), dates = c("4/15/2013", "4/13/2013", "4/15/2013", "4/13/2013", "4/13/2013", "4/15/2013", "4/14/2013", "4/14/2013","4/14/2013" ),values = c(10, 31, 31, 17, 11, 34, 102, 47, 29))

> df
  names     dates values
1     C 4/15/2013     10
2     A 4/13/2013     31
3     A 4/15/2013     31
4     B 4/13/2013     17
5     C 4/13/2013     11
6     B
4/15/2013     34
7     A 4/14/2013    102
8     B 4/14/2013     47
9     C 4/14/2013     29

I need to sort df first on "names" in increasing order and then further on "dates" in a decreasing order i.e. I need

names        dates        values
A            4/15/2013      31
A            4/14/2013     102
A            4/13/2013      31
B            4/15/2013     
34
B            4/14/2013      47
B            4/13/2013      17
C            4/15/2013      10
C            4/14/2013      29
C            4/13/2013      11

I tried

df_sorted = df[order(df$names, (as.Date(df$dates, "%m/%d/%Y")), decreasing = TRUE),]

> df_sorted
  names     dates values
1     C 4/15/2013     10
9     C 4/14/2013     29
5     C 4/13/2013    
11
6     B 4/15/2013     34
8     B 4/14/2013     47
4     B 4/13/2013     17
3     A 4/15/2013     31
7     A 4/14/2013    102
2     A 4/13/2013     31


I need A to appear first with all three corresponding dates in decreasing order, then B and so on.

Please guide.

With regards

Katherine


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