Group Abstract Group Abstract

Message Boards Message Boards

0
|
10.2K Views
|
8 Replies
|
7 Total Likes
View groups...
Share
Share this post:

[?] Delete cases that contain a certain string?

Andrew Burnett
Posted 6 years ago

I am struggling with what I believe is a very simple problem. I have a list of email domains

domains = {"aa.com","bb.com","aa.edu"...}

I want to delete all occurrences of "aa.com". So, I tried

DeleteCases[StringContainsQ[#, "aa.com"] &] /@ domains

Sadly, this doesn't work. Could some kind soul enlighten me on what I did wrong? Cheers Andy
POSTED BY: Andrew Burnett
8 Replies
Sort By:
Rohit Namjoshi
Rohit Namjoshi
Posted 6 years ago

If you have a list of names that you want to delete

domains = {"aa.com", "bb.com", "aa.edu", "baa.com", "cc.bla"};
deletes = {"aa.com", "cc.bla"};
DeleteCases[domains, Alternatives @@ deletes]
(* {"bb.com", "aa.edu", "baa.com"} *)
POSTED BY: Rohit Namjoshi
Andrew Burnett
Andrew Burnett
Posted 6 years ago

Thanks Rohit. You have given me lots to dive into here.

Cheers Andy
POSTED BY: Andrew Burnett 
    domains = {"aa.com", "bb.com", "aa.edu", "baa.com", "cc.bla"};
    DeleteCases[domains, "aa.com"]
(* {"bb.com", "aa.edu", "baa.com", "cc.bla"} *)
POSTED BY: Adriano Pascoletti
Michael Helmle
Michael Helmle
Posted 6 years ago 
domains = {"aa.com", "bb.com", "aa.edu", "baa.com", "cc.bla"}
DeleteCases[domains, _?(StringContainsQ[#, "aa.com"] &)]
POSTED BY: Michael Helmle
Andrew Burnett
Andrew Burnett
Posted 6 years ago

Hi Michael, _?(StringContainsQ[#, "aa.com"] &) Seems to do exactly what I need. However, I am not entirely clear how it works. The help seems to suggest that _?() means match any expression and then return true if the expression in the parenthesis evaluates to true. Have I understood that correctly?

Cheers Andy
POSTED BY: Andrew Burnett
Michael Helmle
Michael Helmle
Posted 6 years ago

Hi Andy, please have look at "PatternTest" in the documentation. DeleteCases requires a pattern as a second argument, and _?test is the pattern that matches everything provided the condition "test" evaluates to True. The parenthesis are required to control the sequence of evaluation due to the high precedence of the ? operator (also described in the docu).

Regards, Michael
POSTED BY: Michael Helmle
POSTED BY: Henrik Schachner
Andrew Burnett
Andrew Burnett
Posted 6 years ago
POSTED BY: Andrew Burnett
Reply to this discussion
Community posts can be styled and formatted using the Markdown syntax.
Tag limit exceeded
Note: Only the first five people you tag will receive an email notification; the other tagged names will appear as links to their profiles.
Reply Preview
Attachments
Remove
or Discard