Rectangle functions in emacs

Question

I\'ve read in several places that the rectangle functions in emacs are very useful. I\'ve read a bit about them, and I can\'t quite figure why. I mean, when you want to kill

Answer 1

If you have data in columns in a text file with M-x delete-rectangle or M-x kill-rectangle you can delete a single column of data. Similarly, M-x yank-rectangle will paste in a column of text.

For example, take the following text:

1. alligator    alphorn
2. baboon       bugle
3. crocodile    cornet
4. dog          didgeridoo
5. elephant     euphonium 
6. fish         flugelhorn   
7. gopher       guitar

Select from the a of alligator to the g of guitar. The beginning and end of the selection mark out two opposite corners of the rectangle. Enter M-x kill-rectangle and you immediately have:

1. alphorn
2. bugle
3. cornet
4. didgeridoo
5. euphonium 
6. flugelhorn
7. guitar

Next put the mark at the end of the top line, add a few spaces if required and enter M-x yank-rectangle and ta-da! You have re-ordered the columns:

1. alphorn      alligator    
2. bugle        baboon       
3. cornet       crocodile    
4. didgeridoo   dog          
5. euphonium    elephant     
6. flugelhorn   fish         
7. guitar       gopher