[R] using function from specific packages

hello, useRs- i have a function that i wrote myself, for example, lag(x). however, when i load 'zoo' packages and try to lag 'zoo' object, it gave me error. (R try to pass 'zoo' object into my function.) i typed 'lag.zoo' in R, but it can't find it. how can i access 'lag.zoo' function? and in

[R] plotting different level of classficifaction

hello, useRs~ suppose i have a matrix as follows: itemcategory sub-category A 1 11 B 1 12 C 1 12 D 2 21 E 2 22 i like to draw a plot that