[R] Value Lookup from File without Slurping

[Gundala Viswanath]

Dear all,

I have a repository file (let's call it repo.txt)
 that contain two columns like this:

# tag  value
AAA    0.2
AAT    0.3
AAC   0.02
AAG   0.02
ATA    0.3
ATT   0.7

Given another query vector

> qr <- c("AAC", "ATT")

I would like to find the corresponding value for each query above,
yielding:

0.02
0.7

However, I want to avoid slurping whole repo.txt into an object (e.g. hash).
Is there any ways to do that?

The reason I want to do that because repo.txt is very2 large size
(milions of lines,
with tag length > 30 bp),  and my PC memory is too small to keep it.

- Gundala Viswanath
Jakarta - Indonesia