[R] Need to abstract changing name of column within loop

[jctoll]

Hi,

I'm struggling to figure out the way to change the name of a column
from within a loop.  The problem is I can't refer to the object by its
actual variable name, since that will change each time through the
loop.  My xts object is A.

> head(A)
           A.Open A.High A.Low A.Close A.Volume A.Adjusted A.Adjusted.1
2007-01-03  34.99  35.48 34.05   34.30  2574600      34.30  11867800000
2007-01-04  34.30  34.60 33.46   34.41  2073700      34.41  11905860000
2007-01-05  34.30  34.40 34.00   34.09  2676600      34.09  11795140000
2007-01-08  33.98  34.08 33.68   33.97  1557200      33.97  11753620000
2007-01-09  34.08  34.32 33.63   34.01  1386200      34.01  11767460000
2007-01-10  34.04  34.04 33.37   33.70  2157400      33.70  11660200000

It's column names are:
> colnames(A)
[1] "A.Open"       "A.High"       "A.Low"        "A.Close"
"A.Volume"     "A.Adjusted"   "A.Adjusted.1"

I want to change the 7th column name:
> colnames(A)[7]
[1] "A.Adjusted.1"

I need to do that through a reference to i:
> i
[1] "A"

This works:
> colnames(get(i))[7]
[1] "A.Adjusted.1"

And this is what I want to change the column name to:
> paste(i, ".MarketCap", sep = "")
[1] "A.MarketCap"

But how do I make the assignment?  This clearly doesn't work:

> colnames(get(i))[7] <-  paste(i, ".MarketCap", sep = "")
Error in colnames(get(i))[7] <- paste(i, ".MarketCap", sep = "") :
  could not find function "get<-"

Nor does this (it creates a new object "A.Adjusted.1" with a value of
"A.MarketCap") :

assign(colnames(get(i))[7], paste(i, ".MarketCap", sep = ""))

How can I change the name of that column within my big loop?  Any
ideas?  Thanks!

Best regards,


James