On 28.10.2012 10:32, Benjamin Ward (ENV) wrote:
Hi All,

I'm trying to run a simulation of host-pathogen evolution based around 
individuals.
What I need to have is a dataframe or table of some description - describing 
all the individuals of a pathogen population (so far I've implemented this as a 
matrix):

          ID         No_of_Effectors                   Effectors (Sequences)
   [1,] 0001              3                   ##   3 Random Numbers ##

There will be many such rows for many individuals. They have something called 
effectors, the number of which is randomly generated, so say you get 3 in the 
No_of_Effectors column. Then I make R generate 3 numbers from between 1 and 
10,000, this gives me three numerical representations of genes. These numbers 
will be compared to a similar data structure of the host individuals who have 
their immune genes with similar numbers.

My problem is that obviously I can't stick 3 numbers in one "cell" of the 
matrix (I've tried) :

Pathogen_Individuals[1,3] <- c(2,3,4)

Consider to use a data.frame with the third column (Effectors) of list type. Then you can do:

Pathogen_Individuals$Effectors[1] <- list(c(2,3,4))

And what you get is:

> Pathogen_Individuals
    ID No_of_Effectors Effectors
1 0001               3   2, 3, 4

Uwe Ligges




Error in Pathogen_Individuals[1, 3] <- c(345, 567, 678) :
   number of items to replace is not a multiple of replacement length

In future I'm also going to have more variables such as whether a gene is 
expressed. Such information may require a matrix in itself - something like:


         Effector ID             Sequence                  Expressed?
   [1,]     0001              345,567,678                       1 (or 0).

Is there a way then I can put more than one value in the cell like a list of values, or a 
way to put objects in a cell of a data frame, matrix or table etc. Almost an inception 
deal - data structures nested in a data structure? If I search for things like 
"insert list into matrix" I get results like how to turn one into another, 
which is not what I think I need to be doing.

I have been considering having several data structures not nested in each 
other, something like for every individual create a new matrix object with the 
name Effectors_[Individual_ID] and some how get my simulation loops operating 
on those objects but I find it hard to see how to tell R all of those matrices 
are to be included in an operation, as you can all lines of a data frame for 
example with for loops.
This is strange for me because this model was written in a macro-code for 
another program which handles data in a different format and layout to R.

My problem is I think, each individual in the model has many variables - in 
this case representations of genes. So I'm having trouble getting my head about 
this.

Hopefully someone more experienced will be able to offer advice or a solution, 
it will be very appreciated.

Many Thanks,
Ben Ward (ENV, UEA & The Sainsbury Lab, JIC).

P.S. I have searched previous queries to the list, and I'm not sure but this 
may be useful for relevant:


Have you thought of using a list?

a <- matrix(1:10, nrow=2)
b <- 1:5
x <- list(a=a, b=b)
x
$a
      [,1] [,2] [,3] [,4] [,5]
[1,]    1    3    5    7    9
[2,]    2    4    6    8   10

$b
[1] 1 2 3 4 5

x$a
      [,1] [,2] [,3] [,4] [,5]
[1,]    1    3    5    7    9
[2,]    2    4    6    8   10
x$b
[1] 1 2 3 4 5

oliveoil and yarn datasets have been mentioned.





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