On 23/07/10 17:36, Duncan Murdoch wrote:
On 23/07/2010 12:10 PM, babyfoxlo...@sina.com wrote:
[...]
You probably won't get much faster than read.table with all of the
colClasses specified. It will be a lot slower if you leave that at
the default NA setting, because then R needs to figure out the types
by reading them as character and examining all the values. If the
file is very consistently structured (e.g. the same number of
characters in every value in every row) you might be able to write a C
function to read it faster, but I'd guess the time spent writing that
would be a lot more than the time saved.
And try the utils::read.fwf() function before you roll your own C code
for this use case.
If you do write C code, consider writing a converter to .RData format
which R seems to read quite efficiently.
Hope this helps.
Allan
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