Ruby Arrays select collect and map

Question

The syntax for mapping   a     a    b    c    d           gt    a    b    c    d    a map   item  a     item         gt   true  false  false  false   a select   item  a     item      gt    a     Question how about if I have    irb main  105 0 gt  details 1     gt    sku  gt  507772-B21    desc  gt  HP 1TB 3G SATA 7 2K RPM LFF  3      qty  gt        qty2  gt  1    price  gt  5 204 34 P     I want to delete every entry which has an empty qty value on this array or select only the ones with some value in it    I tried    details map   item       item    Just returns a lot of false and then when I use the same just change map to select I get

User · Answer

When dealing with a hash     use both the key and value to the block inside the      details map   key item       item     gt  false  false  true  false  false

User · Answer

EDIT  I just realized you want to filter details  which is an array of hashes  In that case you could do  details reject    item  item  qty  empty        The inner data structure itself is not an Array  but a Hash  You can also use select here  but the block is given the key and value in this case   irb main  001 0 gt  h     sku  gt  507772-B21    desc  gt  HP 1TB 3G SATA 7 2K RPM LFF  3      qty  gt      qty2  gt  1    price  gt  5 204 34 P   irb main  002 0 gt  h select    key  value   value empty      gt    sku  gt  507772-B21    desc  gt  HP 1TB 3G SATA 7 2K RPM LFF  3           qty2  gt  1    price  gt  5 204 34 P     Or using reject  which is the inverse of select  excludes all items for which the given condition holds    h reject    key  value  value empty      Note that this is Ruby 1 9  If you have to maintain compatibility with 1 8  you could do   Hash h reject    key  value  value empty

User · Answer

It looks like details is an array of hashes  So item inside of your block will be the whole hash  Therefore  to check the  qty key  you d do something like the following   details select   item  item  qty            That will give you all items where the  qty key isn t an empty string   official select documentation

[ruby] Ruby Arrays: select(), collect(), and map()

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