Please note that this is a cross post.
Originally posted here: r - Read chunkwise and compute 2 variables - Stack Overflow
I wish to read from MySQL database chunkwise, create TWO summary variables and write chunkwise to another table. Here is how I think we may do this seperately as follows(I have not tried the code):
library(RMySQL) library(chunked) library(dplyr) connection <- dbConnect(dbDriver("MySQL"),host = "myhost", db="mydb",user="myuser",password="mypass") # Computing the number of members in a household. tbl(connection,"table1") %>% read_chunkwise() %>% select(hid,year) %>% group_by(hid,year) %>% summarise(Total_members= n()) %>% write_chunkwise("table2") # Extracting the age of the head of household, I know that for # each hid, year there will be only one member with # relation_with_hoh == "hoh" tbl(connection,"table1") %>% read_chunkwise() %>% select(hid,year,relation_with_hoh,age) %>% filter(relation_with_hoh=="hoh") %>% mutate(hoh_age = age) %>% select(hid,year,hoh_age) %>% write_chunkwise("table2")
My question is: How do I these 2 together ?