r - Calculate proportion by groups for a subset of the dataset -

r - Calculate proportion by groups for a subset of the dataset -

this might simple, since im not getting it, im posting here hope help.

i want calculate proportion , standard error of proportion grouping dataset of categorical variables. have 2 variables v1 1 4 , v2 1 9. want calculate proportion of 1 (also 2,3...9 ( in v2)) grouping of v1.

to hand easy because utilize of table(v1, v2), dont want hand :)

said in more simple way: want find % can utilize mean numeric variable. have 1000 people, 300 in category 1 of v1, 200 in category 2 of v1 etc. same v2, 400 in category 1 , on. if calculate % of category 1 (v1) groups of v2, 300/400, 200/400 , on.

dataframe sample

id v1 v2 1 1 1 2 1 1 3 2 1 4 2 1 5 3 2 6 3 2 7 4 2

desired output: propotion grouping v2: grouping 1 (v2=1) 2/4; 2/4; 2/4; 1/4. v2: grouping 2 (v2=2) 2/3; 2/3; 2/3; 1/3

hope makes sense!

try:

library(data.table) setdt(dt)[v1==1,list(meanv2=mean(v2), sev2=se(v2)),by=v3]

if v1==1 , mean(v1) equal 1.

r