# Hash#flatten flattens recursively

**URL:** <https://www.ruby-forum.com/t/hash-flatten-flattens-recursively/128160>\
**Category:** Development\
**Created:** [February 5, 2008, 2:01pm UTC](https://www.ruby-forum.com/t/hash-flatten-flattens-recursively/128160 "2008-02-05T14:01:43Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Yusuke\_ENDOH](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/y/c89c15/32.png) [@Yusuke\_ENDOH](https://www.ruby-forum.com/u/Yusuke_ENDOH)\
**Post date:** [February 5, 2008, 2:01pm UTC](https://www.ruby-forum.com/t/hash-flatten-flattens-recursively/128160/1 "2008-02-05T14:01:43Z")

</div>

e$B1sF#$H?=$7$^$9!#e(B

Hash#flatten e$B$N%3%a%s%H$rFI$`$H!"$3$N%a%=%C%I$O%G%U%)%k%H$G$Oe(B  
e$B:F5"E\*$Ke(B flatten  
e$B$7$J$$$H=q$$$F$"$k$N$G$9$,!"\<B:]$K$O$9$k$h$&$G$9!#e(B

y$ ./ruby -ve ‘p({1 =\> “one”, 2 =\> [2,“two”], 3 =\> “three”}.flatten)’  
ruby 1.9.0 (2008-02-05 revision 15377) [i686-linux]  
[1, “one”, 2, 2, “two”, 3, “three”]

e$B%3%a%s%H$H\<BAu$N$I$A$i$,@5$7$$$N$G$7$g$&$+!#e(B

e$B0J2\<$Oe(B Hash#flatten e$B$N%3%a%s%H$N0zMQ$G$9!#e(B

---

<div class="post-metadata">

**Author:** ![Yusuke\_ENDOH](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/y/c89c15/32.png) [@Yusuke\_ENDOH](https://www.ruby-forum.com/u/Yusuke_ENDOH)\
**Post date:** [February 5, 2008, 5:45pm UTC](https://www.ruby-forum.com/t/hash-flatten-flattens-recursively/128160/2 "2008-02-05T17:45:07Z")

</div>

e$B$^$D$b$He(B e$B$f$-$R$m$G$9e(B

In message “Re: [ruby-dev:33603] Hash#flatten flattens recursively”  
on Tue, 5 Feb 2008 22:00:45 +0900, “Yusuke ENDOH” [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)  
writes:

|Hash#flatten e$B$N%3%a%s%H$rFI$`$H!“$3$N%a%=%C%I$O%G%U%)%k%H$G$Oe(B  
|e$B:F5"E\*$Ke(B flatten e$B$7$J$$$H=q$$$F$”$k$N$G$9$,!"\<B:]$K$O$9$k$h$&$G$9!#e(B  
|  
|y$ ./ruby -ve ‘p({1 =\> “one”, 2 =\> [2,“two”], 3 =\> “three”}.flatten)’  
|ruby 1.9.0 (2008-02-05 revision 15377) [i686-linux]  
|[1, “one”, 2, 2, “two”, 3, “three”]  
|  
|e$B%3%a%s%H$H\<BAu$N$I$A$i$,@5$7$$$N$G$7$g$&$+!#e(B

e$B$J$s$G?)$$0c$C$F$k$N$+$\<$s$\<$s$o$+$i$J$$$s$G$9$,e(B(e$B%3%a%s%H$b\<Be(B  
e$BAu$bN\>J};d$,%A%'%C%/%$%s$7$F$$$ke(B)e$B!";H$$\>!\<j$r9M$($k$H%3%a%s%He(B  
e$BM%@h$NJ}$,NI$$$h$&$J5$$,$7$F$-$^$7$?!#e(B

e$BD\>$7$^$9!#e(B