How to sort a data frame in R

Question

I am new to R, and want to sort a data frame called \"weights\". Here are the details:

>str(weights)
\'data.frame\':   57 obs. of  1 variable:
 $ attr_imp         


        

Answer 1

Here is the big comparison on data.frame sorting:

How to sort a dataframe by column(s)?

Using my now-preferred solution arrange:

dd <- data.frame(b = factor(c("Hi", "Med", "Hi", "Low"), 
      levels = c("Low", "Med", "Hi"), ordered = TRUE),
      x = c("A", "D", "A", "C"), y = c(8, 3, 9, 9),
      z = c(1, 1, 1, 2))
library(plyr)
arrange(dd,desc(z),b)
    b x y z
1 Low C 9 2
2 Med D 3 1
3  Hi A 8 1
4  Hi A 9 1

Answer 2

Since your data.frame only has one column, you need to set drop=FALSE to prevent the dimensions from being dropped:

weights[order(-weights$attr_importance),,drop=FALSE]
#         attr_importance
# our         0.125433292
# all         0.098185517
# address     0.090686474
# over        0.075182467
# make        0.049630556
# num3d       0.007122618

Answer 3

rankdata.txt

regno   name           total    maths   science social cat
1   SUKUMARAN   400 78  89  73  S
2   SHYAMALA    432 65  79  87  S
3   MANOJ       500 90  129 78  C
4   MILYPAULOSE 383 59  88  65  G
5   ANSAL       278 39  77  60  O
6   HAZEENA     273 45  55  56  O
7   MANJUSHA    374 50  99  52  C
8   BILBU       408 81  97  72  S
9   JOSEPHROBIN 374 57  85  68  G
10  SHINY       381 70  79  70  S
z <- data.frame(rankdata)

z[with(z, order(-total+ maths)),]  #order function  maths group selection
z
z[with(z, order(name)),]  # sort on name
z