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 a paragraph, you mark the first row/column and then the last one, and that’s actually a rectangle, right? But you can still use the normal kill…

So what kind of transformations would you do with them?

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