Dr. Mark Gardener

Home
About

Providing training for:

  • Ecology
  • Data analysis
  • Statistics
  • R The statistical programming language
  • Data management
  • Data mining

Tips and Tricks - for R and Excel

On these pages you can find tips, tricks and hints for using both R and Excel. At the end of each tip there are links forwards and backwards as appropriate. There is also an index of R tips and an index of Excel tips.

For most analytical purposes the combination of Excel and R is unbeatable! Excel is great as a data management tool and for preparing data for analysis. You can also use it to get an overview of your data or to make simple (and not so simple) graphs. R is an analytical "swiss army knife" and can carry out a mind-boggling array of analytical routines as well as producing great graphics.

Tips & Tricks for R | Tips & Tricks for Excel | An Introduction to R | MonogRaphs | Writer's Bloc


Use t() to rotate a data.frame or a matrix

The result is always a matrix

A table object can also be rotated using t()

Only 2-D objects can be rotated, check using dim()

colnames() and rownames() attributes are preserved

names() attributes are lost

 

Top

Rotating objects using t()

Two dimensional R objects include data.frame, matrix and table objects. You can transpose the rows and columns using the t() command. Here is a simple data.frame:

> dat = as.data.frame(matrix(1:12, ncol = 4))
> colnames(dat) = LETTERS[1:4]
> dat
A B C D
1 1 4 7 10
2 2 5 8 11
3 3 6 9 12

You can rotate the data.frame so that the rows become the columns and the columns become the rows. That is, you transpose the rows and columns. You simply use the t() command.

> t(dat)
[,1] [,2] [,3]
A 1 2 3
B 4 5 6
C 7 8 9
D 10 11 12

The result of the t() command is always a matrix object.

> dat.t = t(dat)
> class(dat.t)
[1] "matrix"

You can also rotate a matrix object or a table, as long as the table only has 2 dimensions. These items will have rownames() and colnames() elements (even if empty). You can use the dim() command to look at the dimensions of an object.

> dim(HairEyeColor)
[1] 4 4 2

The HairEyeColor table has more than 2 dimensions and so will not rotate:

> t(HairEyeColor)
Error in t.default(HairEyeColor) : argument is not a matrix

However, you can get part of the table (as 2-dimensions):

> HEC = as.table(HairEyeColor[,,1])
> HEC
Eye
Hair Brown Blue Hazel Green
Black 32 11 10 3
Brown 53 50 25 15
Red 10 10 7 7
Blond 3 30 5 8
> class(HEC)
[1] "table"

Now it can be rotated:

> t(HEC)
Hair
Eye Black Brown Red Blond
Brown 32 53 10 3
Blue 11 50 10 30
Hazel 10 25 7 5
Green 3 15 7 8

The colnames() and rownames() elements are preserved (but transposed of course), any names() attributes are lost (since the result is a matrix):

> HEC.t = t(HEC)
> dimnames(HEC.t)
$Eye
[1] "Brown" "Blue"  "Hazel" "Green"
$Hair
[1] "Black" "Brown" "Red"   "Blond"

Summary

  • Use t() to rotate (transpose) data.frame, matrix or table objects with 2-dimensions.
  • Check the dimensions using dim().
  • The result is always a matrix.
  • The colnames() and rownames() attributes are preserved (but transposed).
  • Any names() attributes are lost.

Top << Previous tip: Object elements, [], double [[]] and $ >> Next tip: Sending R output to disk files
 
Follow me...
Facebook Twitter Google+ Linkedin Amazon
Top Tips & Tricks Home Index of R Tips Index of Excel Tips  
More links:

An introduction to R

See my Publications about Excel, R, statistics and data analysis Courses in R, data analysis, data management and statistics Visit the R Project website
 

See my Publications about statistics and data analysis.

MonogRaphs: random topics in R

Writer's Bloc – my latest writing project includes R scripts

Courses in data analysis, data management and statistics.


Top Home
Data Analysis
Contact GardenersOwn Homepage