R - Extract time along with timezone which is part of string [closed] - r

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I have a large database of text, read as data frame with one column of text which has few sentences with time mentioned in different formats as below:
Row 1. I tried to call you on xxx-xxx-xxxx, however reached voice mail I'm scheduling our next follow up on 6/13/2018 between 12 PM and 2 PM PST.
Row 2. I will call you again today if I hear something from them, if not, will call you tomorrow between 4 - 6PM EST.
Row 3. We will await for your reply, if we don't hear from you then we will call you tomorrow between 12:00PM to 2:00PM CST
Row 4. As discussed over the call, we scheduled call back for tomorrow between 12 - 02 PM EST.
Row 5. As suggested by you, we will have our next follow up on 6/13/2018 between 12 PM TO 2 PM PST.
Would like to extract just the time part along with EST/CST/PST.
Expected Outputs:
6/13/2018 4 PM - 6 PM EST
tomorrow 12 PM TO 2 PM PST
Have tried the below:
x <- text$string
sc1 <- str_match(x, " follow up on (.*?) T.")
which returns something like:
follow up on 6/13/2018 between 1 PM TO | 6/13/2018 between 1 PM
Tried to combine other formats using below codes
sc2 <- str_match(x, " will call you tomorrow between (.*?) T.")
and do a rowbind to include both formats (follow up * and will call you*)
sc1rb <- rbind(sc1,sc2)
which did not workk
Any way to extract only the time part along with timezone from the above example strings?
Thanks in advance!

Answer 1

Here's something that works for the sample. As #MrFlick mentioned, please try to share your data in a reproducible way.
Data
> dput(txt)
c("Next follow up on 6/13/2018 between 12 PM and 2 PM PST.",
"will call you tomorrow between 4 - 6PM EST.", "will call you tomorrow between 12:00PM to 2:00PM CST",
"will call you tomorrow between 11 AM to 12 PM EST", "Next follow up on 6/13/2018 between 12 PM TO 2 PM PST."
)
code
> regmatches(txt, regexec('[[:space:]]([[:digit:]]{1,2}[[:space:]].*[[:upper:]]{3})', txt))
[[1]]
[1] " 12 PM and 2 PM PST" "12 PM and 2 PM PST"
[[2]]
[1] " 4 - 6PM EST" "4 - 6PM EST"
[[3]]
character(0)
[[4]]
[1] " 11 AM to 12 PM EST" "11 AM to 12 PM EST"
[[5]]
[1] " 12 PM TO 2 PM PST" "12 PM TO 2 PM PST"
the output is a list wherein each element has two character vectors (read the help section for regmatches). You can simplify this further to get only the output indicated above:
> unname(sapply(txt, function(z){
pattern <- '[[:space:]]([[:digit:]]{1,2}([[:space:]]|:).*[[:upper:]]{3})'
k <- unlist(regmatches(z, regexec(pattern = pattern, z)))
return(k[2])
}))
[1] "12 PM and 2 PM PST" "4 - 6PM EST" "12:00PM to 2:00PM CST" "11 AM to 12 PM EST"
[5] "12 PM TO 2 PM PST"
This based on the sample input. Of course if the input is far too irregular, it'll be hard to use a single regex. If you have such a case, I'd recommend using multiple regex functions that are called one after the other depending on if the preceding ones return NA. Hope this is helpful!

Answer 2

sub(".*?(\\d+\\s*[PA:-].*)","\\1",data)
[1] "12 PM and 2 PM PST." "4 - 6PM EST." "12:00PM to 2:00PM CST"
[4] "11 AM to 12 PM EST" "12 PM TO 2 PM PST."

Answer 3

This code works for almost all your specifications, excepted this substring "4 - 6PM EST". I hope it would be useful on your whole data
data=c(
"Next follow up on 6/13/2018 between 12 PM and 2 PM PST.",
"will call you tomorrow between 4 - 6PM EST.",
"will call you tomorrow between 12:00PM to 2:00PM CST",
"will call you tomorrow between 11 AM to 12 PM EST",
"Next follow up on 6/13/2018 between 12 PM TO 2 PM PST.")
#date exclusion with regex
data=gsub( "*(\\d{1,2}/\\d{1,2}/\\d{4})*", "", data)
#parameters for exlusion and substitution#
excluded_texts=c("Next follow up on","between","will call you tomorrow",":00","\\.")
replaced_input=c(" ","\'-","and","TO"," AM"," PM")
replaced_output=c("","to","to","to","AM","PM")
for (i in excluded_texts){
data=gsub(i, "", data)}
for (j in 1:length(replaced_input)){
data=gsub(replaced_input[j],replaced_output[j],data)
}
print(data)