UNIX and Linux Applications

Hi all,

I posted the same message under 'Kaleidagraph like software for Ubuntu' thread. I guess there may not be many people familiar with Kaleidagraph.
So I post my message under another subject name.

I need a tool for Ubuntu 8.10,
-which is quick and easy to learn and use (as I am running out of time until deadline)
-which is able to handle large amount of data-i.e., I should be able to open a code output written in a text format, tab or space delimited
-which is able to create plots based on the columns of the table

GNUplot is fine for plotting, however, I cannot play around the data.
Spreadsheet cannot open .txt or .dat.
Grace is a bit complicated, I could not see in the tutorials how I can view my data columns.
Kaleidagraph is really good, but it is for Mac and Windows only.

Any suggestions?

Many thanks!

---------- Post updated 07-23-09 at 01:15 PM ---------- Previous update was 07-22-09 at 06:39 PM ----------

In case some other user may need the info:

Qtiplot is pretty much like Kaleidagraph.

For what it is worth, R (r-project.org) and jpgraph (auditus.nu) are the packages that you will encounter a lot.