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rsqliteany

Use any() to fetch data from SQLite database using dbplyr


I want to fetch data from a local SQLite database in R by using the any() function in combination with group_by to filter groups where at least one row is equal to a certain condition. It would probably help to finally learn SQL, however, until now I managed to do all my queries using dbplyr and I hope there is a dplyr solution for this problem as well.

db <- dbConnect(RSQLite::SQLite(), "test_db.sqlite")

test_table <- tibble(id = c(rep(1:3, each = 3)),
                     cond = c(rep("A", 8), "B"))

dbWriteTable(db, "table", test_table)

table <- tbl(db, "table")

With the table already in memory I can accomplish what I want easily using

test_table %>% 
  group_by(id) %>% 
  filter(any(cond == "B"))

which gives me

     id cond 
  <int> <chr>
1     3 A    
2     3 A    
3     3 B    

However this does not work:

table %>% 
  group_by(id) %>% 
  filter(any(cond == "B"))

It results in the following error:

error: no such function: any

Is there a dbplyr workaround?


Solution

  • Here is a solution that works:

    library(dplyr)
    library(DBI)
    
    db <- dbConnect(RSQLite::SQLite(), "test_db.sqlite")
    
    test_table <- tibble(id = c(rep(1:3, each = 3)),
                         cond = c(rep("A", 8), "B"))
    test_table
    ### A tibble: 9 × 2
    ##     id cond 
    ##  <int> <chr>
    ##1     1 A    
    ##2     1 A    
    ##3     1 A    
    ##4     2 A    
    ##5     2 A    
    ##6     2 A    
    ##7     3 A    
    ##8     3 A    
    ##9     3 B    
    
    
    dbWriteTable(db, "table", test_table)
    
    table <- tbl(db, "table")
    
    table %>%
      group_by(id) %>%
      filter(sum(cond == "B") > 0)
    
    ## Source:   lazy query [?? x 2]
    ## Database: sqlite 3.38.0 [test_db.sqlite]
    ## Groups:   id
    #     id cond 
    #  <int> <chr>
    #1     3 A    
    #2     3 A    
    #3     3 B