Marking axes at irregular intervals

[strontium90]

Hello everyone,

I have two vectors, x in [-1 100] and y in [0 100] that I would like to 
plot y versus x. However, I would like to have the x and y axes marked 
and labeled at the locations of vector components, for example 1, 2, 3, 
4, 5, 10, 15, 20, ... on the x axis, preferably preserving aspect ratio. 
Function plot systematically divides the axes at equal intervals 20, 40, 
60, 80 and 100. Discrete functions bar and hist behave similarly. I'm 
unable to come up with a solution with the function axis.
All tips are greatly appreciated. Thanks!

--Razmig