Hello to everyone!

Can everyone halps me in R code to aggregate this dataframe abundance based on samples. Then to put in order dataframe based on abundance of "others", so if in the human sample "others" are more then human sample written bacteria, arrange it in the bottom of dataframe. And compute the same for other samples. This is the part of my dataframe:

samples         |   abundance           |     bacteria 

human           |   0.0010928962        |     Lactobacillus

human           |   0.0109282828        |     Bifidobacterium

human           |   0.0001366120        |     others

mice            |   0.0003005464        |     Lactobacillus

mice            |   0.000609838         |     Lactobacillus

mice            |   0.0004918033        |     others

rat             |   0.000309838         |     Bifidobacterium

human           |   0.0861612022        |     Bifidobacterium

rat             |   0.1801775956        |     Bifidobacterium

mice            |   0.1801775956        |     Bifidobacterium

rat             |   0.0011110220        |     Lactobacillus