How do I remove blank elements from an array

Question

I have the following array   cities     Kathmandu    Pokhara        Dharan    Butwal     I want to remove blank elements from the array and want the following result   cities     Kathmandu    Pokhara    Dharan    Butwal     Is there any method like compact that will do it without loops

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There are already a lot of answers but here is another approach if you re in the Rails world    cities     Kathmandu    Pokhara        Dharan    Butwal   select  amp  present

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compact blank  Rails 6 1   If you are using Rails  or a standalone ActiveSupport   starting from version 6 1  there is a compact blank method which removes blank values from arrays  It uses Object blank  under the hood for determining if an item is blank    quot Kathmandu quot    quot Pokhara quot    quot  quot    quot Dharan quot   nil   quot Butwal quot   compact blank     gt    quot Kathmandu quot    quot Pokhara quot    quot Dharan quot    quot Butwal quot     1   quot  quot   nil  2   quot   quot           false  true  compact blank     gt   1  2  true   Here is a link to the docs and a link to the relative PR  A destructive variant is also available  See Array compact blank    If you need to remove only nil values  please  consider using Ruby build-in Array compact and Array compact  methods    quot a quot   nil   quot b quot   nil   quot c quot   nil  compact     gt    quot a quot    quot b quot    quot c quot

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Update with a strict with join  amp  split  cities     Kathmandu    Pokhara        Dharan    Butwal   cities join      split   Result will be     Kathmandu    Pokhara    Dharan    Butwal     Note that  this doesn t work with a city with spaces

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Here is one more approach to achieve this  we can use presence with select  cities     Kathmandu    Pokhara        Dharan   nil   Butwal    cities select  amp  presence     Kathmandu    Pokhara    Dharan    Butwal

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Shortest way cities select  amp  present

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Try this   puts   Kathmandu    Pokhara        Dharan    Butwal   -

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You can Try this   cities reject   amp  empty

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cities     Kathmandu    Pokhara        Dharan    Butwal   delete if   c  c empty

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When I want to tidy up an array like this I use     Kathmandu    Pokhara        Dharan    Butwal   -      nil    This will remove all blank or nil elements

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In my project I use delete   cities delete

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Plain Ruby  values    1 2 3   quot   quot    quot  quot    quot  quot   nil  -   quot  quot    quot   quot   nil  puts values    1 2 3

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Here is a solution if you have mixed types in your array    nil  some string here     4 3 2    Solution    nil  some string here     4 3 2  compact reject  r  r empty  if r class    String    Output     gt    some string here   4  3  2

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1 9 3p194  001  gt        A    B    C       reject  amp  empty      gt    A    B    C

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another method    gt    a   b   c         f   g   keep if  some  some present     gt    a   b   c   f   g

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To remove nil values do     a   nil   b   compact     o p   gt     quot a quot    quot b quot    To remove empty strings       a    b       select   a   a empty       o p   gt    quot a quot    quot b quot    To remove both nil and empty strings    a   nil   b       select   a  a present        o p   gt    quot a quot    quot b quot

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Here is what works for me    1      2   hello   nil  reject  amp  blank     output     1  2   hello

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Most Explicit  cities delete if  amp  blank     This will remove both nil values and empty string      values   For example   cities     Kathmandu    Pokhara        Dharan    Butwal   nil   cities delete if  amp  blank       gt    Kathmandu    Pokhara    Dharan    Butwal

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There are many ways to do this  one is reject  noEmptyCities   cities reject    c  c empty      You can also use reject   which will modify cities in place  It will either return cities as its return value if it rejected something  or nil if no rejections are made  That can be a gotcha if you re not careful  thanks to ninja08 for pointing this out in the comments

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Use reject    gt  gt  cities     Kathmandu    Pokhara        Dharan    Butwal   reject   e  e empty      gt    Kathmandu    Pokhara    Dharan    Butwal

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cities reject     c  c blank      The reason you want to use blank  over empty  is that blank recognizes nil  empty strings  and white space  For example   cities     Kathmandu    Pokhara        nil       Dharan    Butwal   reject    c  c blank      would still return     Kathmandu    Pokhara    Dharan    Butwal     And calling empty  on     will return false  which you probably want to be true   Note  blank  is only accessible through Rails  Ruby only supports empty

[ruby] How do I remove blank elements from an array?

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