Feature extraction from the text I am a newbie in machine learning but I have a coursework to create program that can extract some concrete features from the given text.

For example:
If I want to extract number of red apples and green apples, I will extract 3, 5 from "On that tree 3 red apples and 5 green apples grow" and 10, 1000 from "In the box there are 1000 green apples and 10 of red".
Actually the real examples can be more complicated like a extracting a car specification from the ad.

The concrete features are known before the data set processing.

Could you suggest what kind of algorithms I should use? Previously, I used only linear regression.
I guess if you know what you want to extract you can just find it using regular expressions for integers or car specifications.