filter()
命令并观察到意外行为:
如果我用
filter(pos == variable)
filter(pos == 12345)
工作-结果的变化,因为它应该为每个不同的值我过滤。
这是一个懒惰的评估或整洁的方面?正确的方法是什么
筛选器()
使用变量的DB-backed tible?
library(dplyr)
con <- DBI::dbConnect(RSQLite::SQLite(), path = ":dbname:")
ex_data <- tibble(
pos = c(10510138, 10510507),
ref = c("CATA", "TCA"),
alt = c("C", "T")
)
copy_to(con, ex_data, "variants", temporary = FALSE)
toQueryDB <- tbl(con, "variants")
pos = 10510138
(result <- toQueryDB %>% filter(pos == pos) %>% select(pos, ref, alt) %>% head(1))
# 10510138 CATA C
pos = 10510507
(result <- toQueryDB %>% filter(pos == pos) %>% select(pos, ref, alt) %>% head(1))
# STILL 10510138 CATA C !!!
(result <- toQueryDB %>% filter(pos == 10510138) %>% select(pos, ref, alt) %>% head(1))
# 10510138 CATA C
(result <- toQueryDB %>% filter(pos == 10510507) %>% select(pos, ref, alt) %>% head(1))
# 10510507 TCA T
DBI::dbDisconnect(con)
以及我的会话信息:
> sessionInfo()
R version 3.5.1 (2018-07-02)
Platform: x86_64-apple-darwin15.6.0 (64-bit)
Running under: macOS Sierra 10.12.6
Matrix products: default
BLAS: /System/Library/Frameworks/Accelerate.framework/Versions/A/Frameworks/vecLib.framework/Versions/A/libBLAS.dylib
LAPACK: /Library/Frameworks/R.framework/Versions/3.5/Resources/lib/libRlapack.dylib
locale:
[1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8
attached base packages:
[1] stats graphics grDevices utils datasets methods base
other attached packages:
[1] dplyr_0.7.6
loaded via a namespace (and not attached):
[1] Rcpp_0.12.18 rstudioapi_0.7 bindr_0.1.1 magrittr_1.5 tidyselect_0.2.4 bit_1.1-14 R6_2.2.2
[8] rlang_0.2.2 fansi_0.3.0 blob_1.1.1 tools_3.5.1 utf8_1.1.4 cli_1.0.1 DBI_1.0.0
[15] dbplyr_1.2.2 yaml_2.2.0 bit64_0.9-7 assertthat_0.2.0 digest_0.6.17 tibble_1.4.2 crayon_1.3.4
[22] bindrcpp_0.2.2 purrr_0.2.5 memoise_1.1.0 glue_1.3.0 RSQLite_2.1.1 compiler_3.5.1 pillar_1.3.0
[29] pkgconfig_2.0.2
