one more "?" operator bug?

[cbarbu]

[0-9] n times and [0-9]{n} behave differently when used with ? before:

a<-c("/Cajon_Criolla_20141024",

•  "/Linon_20141115_20141130",
  

•  "/Cat/LIQUID",
  

•  "/c_puertas_20141206_20141107",
  

•  "/C_Puertas_3_20141017_20141018",
  

•  "/c_puertas_navidad_20141204_20141205"
  

•  )
  

sub("(.?)([0-9]{8})(.)$","\2",a)
[1] "20141024" "20141130" "/Cat/LIQUID" "20141107" "20141018"
[6] "20141205"
sub("(.?)([0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9])(.)$","\2",a)
[1] "20141024" "20141115" "/Cat/LIQUID" "20141206" "20141017"
[6] "20141204"

likely related to bugs #11 and #21 . See also original post on SO:

http://stackoverflow.com/questions/28725115/r-regex-capture-numbers-in-string-and-replacing-them-in-another-column-captu/28725655