将列分隔成多行，并在左边填入R

I've got a very long list of annotated genes. They are annotated at varying levels "A", "B", "C", etc. Each level has a different name and in some cases a different format. I'd like to keep the names of each level intact. In R, the text document gets imported as 1 column, and I'd like to separate A, B, C, and D rows into columns. Rows are in order, meaning "B Level2" is listed after the application A Level1 category and above "C Level3" category. "#" separate level D, from the next A levell category. SO, after each "#" I'd like to separate the A, B, C, and D rows into separate columns. THEN fill in the column to the left with the level category name above. Given this example df:I've got a very long list of annotated genes. T