Hi, 

Just use the function left_join from the package dplyr. If you have the exact same column names for shared variables in the your two dataframes, just write: 

library("dplyr")

?dplyr::left_join

left_join(long_dataframe_name, short_dataframe_name)

You can also specify the "by" argument, to force the join using a single or few variables  

left_join(long_dataframe_name, short_dataframe_name, by= c("Age", "Gender"))

Best,

Hi, 

Just use the function left_join from the package dplyr. If you have the exact same column names for shared variables in the your two dataframes, just write: 

library("dplyr")

?dplyr::left_join

left_join(long_dataframe_name, short_dataframe_name)

You can also specify the "by" argument, to force the join using a single or few variables  

left_join(long_dataframe_name, short_dataframe_name, by= c("Age", "Gender"))

Best,

left_join is a great way to do this

data_frame_a %>%

left_join(data_frame_b, by = c("Age", "Gender") 

Logical operators work with dates as long as they are identified as dates in the tibble or df so you can then run a filter through the df such as

data_frame_a %>%

left_join(data_frame_b, by = c("Age", "Gender")  %>%

filter(DateTime_Event < Date_time_end & DateTime_Event > Date_time_begin) 

should work in my experience with similar data, but there are screwy things with dates.

If they are not recognized as dates, you should look into lubridate and maybe clean them up.