What does _. mean in patterns?

The name of the pictureThe name of the pictureThe name of the pictureClash Royale CLAN TAG#URR8PPP











up vote
3
down vote

favorite
1












Here is a quick one, hopefully. I searched through different tutorials and documentation articles but haven't been able to find anything yet.



What does _. mean? As in _,_. as opposed to _,_ or _,_,_. as opposed to _,_,_?



Thanks!






pattern-matching argument-patterns







share|improve this question





















  • I may have found it - it might represent Default, but I have to do some more reading.
    – Jmeeks29ig
    2 hours ago










  • That seems to make sense. I am trying to use it in context of pattern matching, using SyntaxInformation, to get the required arguments of some random function, and then insert values into the function in the proper order
    – Jmeeks29ig
    2 hours ago










  • @Szabolcs You forgot a /. coef_. a :> coef :)
    – xzczd
    2 hours ago






  • 1




    @xzczd You are right. I deleted my comment (it was incorrect).
    – Szabolcs
    2 hours ago






  • 2




    "I searched through different tutorials and documentation articles but haven't been able to find anything yet." Then you haven't yet learned the correct usage of document: i.stack.imgur.com/RVvvv.gif
    – xzczd
    2 hours ago














up vote
3
down vote

favorite
1












Here is a quick one, hopefully. I searched through different tutorials and documentation articles but haven't been able to find anything yet.



What does _. mean? As in _,_. as opposed to _,_ or _,_,_. as opposed to _,_,_?



Thanks!






pattern-matching argument-patterns







share|improve this question





















  • I may have found it - it might represent Default, but I have to do some more reading.
    – Jmeeks29ig
    2 hours ago










  • That seems to make sense. I am trying to use it in context of pattern matching, using SyntaxInformation, to get the required arguments of some random function, and then insert values into the function in the proper order
    – Jmeeks29ig
    2 hours ago










  • @Szabolcs You forgot a /. coef_. a :> coef :)
    – xzczd
    2 hours ago






  • 1




    @xzczd You are right. I deleted my comment (it was incorrect).
    – Szabolcs
    2 hours ago






  • 2




    "I searched through different tutorials and documentation articles but haven't been able to find anything yet." Then you haven't yet learned the correct usage of document: i.stack.imgur.com/RVvvv.gif
    – xzczd
    2 hours ago












up vote
3
down vote

favorite
1









up vote
3
down vote

favorite
1






1





Here is a quick one, hopefully. I searched through different tutorials and documentation articles but haven't been able to find anything yet.



What does _. mean? As in _,_. as opposed to _,_ or _,_,_. as opposed to _,_,_?



Thanks!






pattern-matching argument-patterns







share|improve this question













Here is a quick one, hopefully. I searched through different tutorials and documentation articles but haven't been able to find anything yet.



What does _. mean? As in _,_. as opposed to _,_ or _,_,_. as opposed to _,_,_?



Thanks!






pattern-matching argument-patterns




pattern-matching argument-patterns






share|improve this question













share|improve this question











share|improve this question




share|improve this question










asked 2 hours ago









Jmeeks29ig

3066




3066











  • I may have found it - it might represent Default, but I have to do some more reading.
    – Jmeeks29ig
    2 hours ago










  • That seems to make sense. I am trying to use it in context of pattern matching, using SyntaxInformation, to get the required arguments of some random function, and then insert values into the function in the proper order
    – Jmeeks29ig
    2 hours ago










  • @Szabolcs You forgot a /. coef_. a :> coef :)
    – xzczd
    2 hours ago






  • 1




    @xzczd You are right. I deleted my comment (it was incorrect).
    – Szabolcs
    2 hours ago






  • 2




    "I searched through different tutorials and documentation articles but haven't been able to find anything yet." Then you haven't yet learned the correct usage of document: i.stack.imgur.com/RVvvv.gif
    – xzczd
    2 hours ago
















  • I may have found it - it might represent Default, but I have to do some more reading.
    – Jmeeks29ig
    2 hours ago










  • That seems to make sense. I am trying to use it in context of pattern matching, using SyntaxInformation, to get the required arguments of some random function, and then insert values into the function in the proper order
    – Jmeeks29ig
    2 hours ago










  • @Szabolcs You forgot a /. coef_. a :> coef :)
    – xzczd
    2 hours ago






  • 1




    @xzczd You are right. I deleted my comment (it was incorrect).
    – Szabolcs
    2 hours ago






  • 2




    "I searched through different tutorials and documentation articles but haven't been able to find anything yet." Then you haven't yet learned the correct usage of document: i.stack.imgur.com/RVvvv.gif
    – xzczd
    2 hours ago















I may have found it - it might represent Default, but I have to do some more reading.
– Jmeeks29ig
2 hours ago




I may have found it - it might represent Default, but I have to do some more reading.
– Jmeeks29ig
2 hours ago












That seems to make sense. I am trying to use it in context of pattern matching, using SyntaxInformation, to get the required arguments of some random function, and then insert values into the function in the proper order
– Jmeeks29ig
2 hours ago




That seems to make sense. I am trying to use it in context of pattern matching, using SyntaxInformation, to get the required arguments of some random function, and then insert values into the function in the proper order
– Jmeeks29ig
2 hours ago












@Szabolcs You forgot a /. coef_. a :> coef :)
– xzczd
2 hours ago




@Szabolcs You forgot a /. coef_. a :> coef :)
– xzczd
2 hours ago




1




1




@xzczd You are right. I deleted my comment (it was incorrect).
– Szabolcs
2 hours ago




@xzczd You are right. I deleted my comment (it was incorrect).
– Szabolcs
2 hours ago




2




2




"I searched through different tutorials and documentation articles but haven't been able to find anything yet." Then you haven't yet learned the correct usage of document: i.stack.imgur.com/RVvvv.gif
– xzczd
2 hours ago




"I searched through different tutorials and documentation articles but haven't been able to find anything yet." Then you haven't yet learned the correct usage of document: i.stack.imgur.com/RVvvv.gif
– xzczd
2 hours ago










2 Answers
2






active

oldest

votes

















up vote
5
down vote



accepted










In[5]:= FullForm[_.]

Out[5]= Optional[Blank]


See Optional and Blank.






share|improve this answer




















  • Thanks! I'm still learning some of the basics, I should have thought to use FullForm :)
    – Jmeeks29ig
    1 hour ago

















up vote
1
down vote













I'm not sure if this fully answers the question I posted, but after some more searching, I have discovered that it seems like _. evaluates to Optional, at least when using ReplaceAll. An example will be better than words:



_, _. /. _Blank -> g


evaluates to:



g, Optional[g]


I know this is not a full answer, but hopefully it is at least partially helpful.






share|improve this answer




















    Your Answer




    StackExchange.ifUsing("editor", function ()
    return StackExchange.using("mathjaxEditing", function ()
    StackExchange.MarkdownEditor.creationCallbacks.add(function (editor, postfix)
    StackExchange.mathjaxEditing.prepareWmdForMathJax(editor, postfix, [["$", "$"], ["\\(","\\)"]]);
    );
    );
    , "mathjax-editing");

    StackExchange.ready(function()
    var channelOptions =
    tags: "".split(" "),
    id: "387"
    ;
    initTagRenderer("".split(" "), "".split(" "), channelOptions);

    StackExchange.using("externalEditor", function()
    // Have to fire editor after snippets, if snippets enabled
    if (StackExchange.settings.snippets.snippetsEnabled)
    StackExchange.using("snippets", function()
    createEditor();
    );

    else
    createEditor();

    );

    function createEditor()
    StackExchange.prepareEditor(
    heartbeatType: 'answer',
    convertImagesToLinks: false,
    noModals: false,
    showLowRepImageUploadWarning: true,
    reputationToPostImages: null,
    bindNavPrevention: true,
    postfix: "",
    onDemand: true,
    discardSelector: ".discard-answer"
    ,immediatelyShowMarkdownHelp:true
    );



    );













     

    draft saved


    draft discarded


















    StackExchange.ready(
    function ()
    StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmathematica.stackexchange.com%2fquestions%2f181826%2fwhat-does-mean-in-patterns%23new-answer', 'question_page');

    );

    Post as a guest

















    2 Answers
    2






    active

    oldest

    votes








    2 Answers
    2






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes








    up vote
    5
    down vote



    accepted










    In[5]:= FullForm[_.]

    Out[5]= Optional[Blank]


    See Optional and Blank.






    share|improve this answer




















    • Thanks! I'm still learning some of the basics, I should have thought to use FullForm :)
      – Jmeeks29ig
      1 hour ago














    up vote
    5
    down vote



    accepted










    In[5]:= FullForm[_.]

    Out[5]= Optional[Blank]


    See Optional and Blank.






    share|improve this answer




















    • Thanks! I'm still learning some of the basics, I should have thought to use FullForm :)
      – Jmeeks29ig
      1 hour ago












    up vote
    5
    down vote



    accepted







    up vote
    5
    down vote



    accepted






    In[5]:= FullForm[_.]

    Out[5]= Optional[Blank]


    See Optional and Blank.






    share|improve this answer












    In[5]:= FullForm[_.]

    Out[5]= Optional[Blank]


    See Optional and Blank.







    share|improve this answer












    share|improve this answer



    share|improve this answer










    answered 1 hour ago









    Jason B.

    46k382176




    46k382176











    • Thanks! I'm still learning some of the basics, I should have thought to use FullForm :)
      – Jmeeks29ig
      1 hour ago
















    • Thanks! I'm still learning some of the basics, I should have thought to use FullForm :)
      – Jmeeks29ig
      1 hour ago















    Thanks! I'm still learning some of the basics, I should have thought to use FullForm :)
    – Jmeeks29ig
    1 hour ago




    Thanks! I'm still learning some of the basics, I should have thought to use FullForm :)
    – Jmeeks29ig
    1 hour ago










    up vote
    1
    down vote













    I'm not sure if this fully answers the question I posted, but after some more searching, I have discovered that it seems like _. evaluates to Optional, at least when using ReplaceAll. An example will be better than words:



    _, _. /. _Blank -> g


    evaluates to:



    g, Optional[g]


    I know this is not a full answer, but hopefully it is at least partially helpful.






    share|improve this answer
























      up vote
      1
      down vote













      I'm not sure if this fully answers the question I posted, but after some more searching, I have discovered that it seems like _. evaluates to Optional, at least when using ReplaceAll. An example will be better than words:



      _, _. /. _Blank -> g


      evaluates to:



      g, Optional[g]


      I know this is not a full answer, but hopefully it is at least partially helpful.






      share|improve this answer






















        up vote
        1
        down vote










        up vote
        1
        down vote









        I'm not sure if this fully answers the question I posted, but after some more searching, I have discovered that it seems like _. evaluates to Optional, at least when using ReplaceAll. An example will be better than words:



        _, _. /. _Blank -> g


        evaluates to:



        g, Optional[g]


        I know this is not a full answer, but hopefully it is at least partially helpful.






        share|improve this answer












        I'm not sure if this fully answers the question I posted, but after some more searching, I have discovered that it seems like _. evaluates to Optional, at least when using ReplaceAll. An example will be better than words:



        _, _. /. _Blank -> g


        evaluates to:



        g, Optional[g]


        I know this is not a full answer, but hopefully it is at least partially helpful.







        share|improve this answer












        share|improve this answer



        share|improve this answer










        answered 1 hour ago









        Jmeeks29ig

        3066




        3066



























             

            draft saved


            draft discarded















































             


            draft saved


            draft discarded














            StackExchange.ready(
            function ()
            StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmathematica.stackexchange.com%2fquestions%2f181826%2fwhat-does-mean-in-patterns%23new-answer', 'question_page');

            );

            Post as a guest
































































            Comments

            Post a Comment

            Popular posts from this blog

            Long meetings (6-7 hours a day): Being “babysat” by supervisor

            Image
            Clash Royale CLAN TAG #URR8PPP .everyoneloves__top-leaderboard:empty,.everyoneloves__mid-leaderboard:empty margin-bottom:0; up vote 31 down vote favorite 4 I hold a PhD in mechanical engineering with a 7 year background in self-guided, self-paced research including 2 years as a graduate level course instructor and a subject matter expert for various engineering projects in a university setting in the United States. For the last 10-11 months, I am working in a research industry in France where my task is to debug C++ spaghetti code written over a period of several years by my current supervisor. It is a team of 2: just I and my supervisor. Diurnally, I am posed with a "bug of the day" to get out of this C++ code. My supervisor generally gives me about 15-30 minutes to solve it and then accosts me about whether or not the task is completed and then rinses and repeats this until the end of the day. Off-late, my supervisor has been holding 6-7 hour long "meetin
            Read more

            Is the Concept of Multiple Fantasy Races Scientifically Flawed? [closed]

            Image
            Clash Royale CLAN TAG #URR8PPP up vote 2 down vote favorite Many fantasy worlds have multiple humanoid species (elves, orcs, humans, etc) living in the same world, in addition to that, they often have the ability to interbreed. And I can't help but question their believability... fantasy-races reproduction interspecies-relations share | improve this question edited Aug 9 at 14:46 Michael Kjörling ♦ 21.1k 10 85 161 asked Aug 9 at 13:13 Chlodio 118 6 closed as unclear what you're asking by MichaelK, Gryphon, John, Vincent, Frostfyre Aug 9 at 15:25 Please clarify your specific problem or add additional details to highlight exactly what you need. As it's currently written, it’s hard to tell exactly what you're asking. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question. 3 Stack Exchange exist to
            Read more

            Confectionery

            Image
            Prepared foods made with a lot of sugar or other cabohydrates "Sweetmeat" redirects here. For the racehorse, see Sweetmeat (horse). Not to be confused with Sweetbread. This Kransekake is a traditional Scandinavian baker's confection. Confectionery is the art of making confections , which are food items that are rich in sugar and carbohydrates. Exact definitions are difficult. [1] In general, though, confectionery is divided into two broad and somewhat overlapping categories, bakers' confections and sugar confections. [2] Bakers' confectionery, also called flour confections , includes principally sweet pastries, cakes, and similar baked goods. Sugar confectionery includes candies ( sweets in British English), candied nuts, chocolates, chewing gum, bubble gum, pastillage, and other confections that are made primarily of sugar. In some cases, chocolate confections (confections made of chocolate) are treated as a separate category, as are sugar-free versions of
            Read more