Why has Novak Djokovic been on both sides of the #1 and #2's draw for most grand slam tournaments.?

Question

I'm pretty confused about which side of the draw the #3 seed belongs to. I'm not a fan of Nole (I'm actually both a fan of Federer and Nadal) but in the Australian open this year, he was on Federer's (who at the time, was #1) half of the draw in the semifinals. BUT in the French Open, he was in Nadal's (who at the time was #2) half of the draw and played each other in the semifinals. THEN when he played in Wimbledon, had he beaten Marat Safin, he would've played Federer (still #1 at the time) in the semifinals. Explain please?

Answer 1

after the 1 and 2 seeds have been determined they randomly draw (sumtimes out of a hat) wat half of the draw the number 3 seed will be on. so nole can end up on rafa or rogers half since its randomly picked

Answer 2

The number 1 & 2 are always on opposite sides of the draw.  After that, they tournament officials flip a coin to see which side the #s 3 and 4 will go on.  Sometimes the 1 plays the 4, other times the 1 plays the 3 and the 2 plays the 4.