In R 1.9.0, make.names will accept "_" as a valid character for a syntactically valid name.
I would appreciate to have an option in ``read.delim'' (etc.) that would change "_" in headers of input files to "." for compatibility with code and data written for R 1.8.1 and before.
Given that you are going to have to change your code to invoke this parameter, you may as well just write a 'makeOldStyleNames' function and call that.
For example, suppose you currently have:
myData = read.table("data.csv",sep=",",head=T)
print(myData$foo.1)and the data file has a column 'foo_1' which has been renamed to foo.1.
If the option is added to read.table, you'll have to change your code to something like:
myData = read.table("data.csv", sep=",", head=T, oldNames=T)
Now that would break in pre-1.9.0 releases. However, if you do:
myData = read.table("data.csv", sep=",", head=T)
names(myData) = makeOldStyleNames(names(myData))then, as long as makeOldStyleNames doesn't do anything to old style (dotted) names, and works in 1.8 and 1.9, you have achieved your goal and got back-compatibility as well.
The makeOldStyleNames could be quite tricky - just replacing '_' with '.' might break if you have 'foo_1' and 'foo.1' in your data frame.
Perhaps doing the replacement and then calling R's make.names() with 'unique=T' will work - depending on what 1.9 does in make.unique.
Baz
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