r - Reducing data frame by linear regression -

i reduce following data frame:

subject, run, condition, dv 1, 1, 1, 123 1, 1, 2, 456 1, 1, 3, 789 1, 2, 1, 123 1, 2, 2, 456 1, 2, 3, 789 2, 1, 1, 123 2, 1, 2, 456 2, 1, 3, 789 2, 2, 1, 123 2, 2, 2, 456 2, 2, 3, 789 

to data frame:

subject, run, coeff(lm(dv ~ condition)) 1, 1, ??? 1, 2, ??? 2, 1, ??? 2, 2, ??? 

any ideas on how approach this?

you should use do rather summarize:

df %>% group_by(subject, run) %>%   do(lm = lm(dv ~ condition,data=.)) %>%    summarize(subject=subject,             run=run,             coef=coef(lm)[[2]])