Crontab 部署 R 爬蟲時需要注意的地方.md

Crontab 部署 R 爬蟲時需要注意的地方

1. rvest::html_table 需要 import methods，稍微查過僅有 {xml2} -> {testhat} -> {methods}
2. （測試用），在blogger會變白色....

This thread might shed some light on it. It seems that in some contexts RSCRIPT doesn't load package::methods by default, whereas interactive sessions do load it by default. It seems that the "when" is not clear, but explicitly calling library(methods) for all RSCRIPT executions seems to be the safe bet: can use package interactively, but Rscript gives errors.

感謝 kyle大大 指導，釐清與magrittr無關

echo 'library(magrittr); tt <- list(a=1,b=2); tt %>% .[[1]]' > tt.R && Rscript tt.R

ref

• http://stackoverflow.com/questions/35351443/rvest-html-nodes-error-cannot-coerce-type-environment-to-vector-of-type-l