Kevin Powell - Community•5mo ago

How do I make an array from specific keys in another array?

OK, I'm exhausted after spending 10 hours researching and testing, but to no avail. I have an array, which is along the lines of ...

[
 - {
    - 0: {
          firstname: "John",
          lastname: "Johnson",
          age: "34",
          etc: "",
          etc: "",
          etc: ""
      },
    - 1: {
          firstname: "David",
          lastname: "Davidson",
          age: "45",
          etc: "",
          etc: "",
          etc: ""
      },
    - 2: {
          firstname: "Peter",
          lastname: "Peterson",
          age: "56",
          etc: "",
          etc: "",
          etc: ""

      },
    - 3: {
          firstname: "Robert",
          lastname: "Robertson",
          age: "67",
          etc: "",
          etc: "",
          etc: ""
        }
    }
]

[
 - {
    - 0: {
          firstname: "John",
          lastname: "Johnson",
          age: "34",
          etc: "",
          etc: "",
          etc: ""
      },
    - 1: {
          firstname: "David",
          lastname: "Davidson",
          age: "45",
          etc: "",
          etc: "",
          etc: ""
      },
    - 2: {
          firstname: "Peter",
          lastname: "Peterson",
          age: "56",
          etc: "",
          etc: "",
          etc: ""

      },
    - 3: {
          firstname: "Robert",
          lastname: "Robertson",
          age: "67",
          etc: "",
          etc: "",
          etc: ""
        }
    }
]

How do I create a new array to contain only firstnames and lastnames please?

19 Replies

ἔρως•5mo ago

select firstname, lastname from table

BlackwolfOP•5mo ago

do you know what, i just realised that as i read it back i've been playing with the complete array

ἔρως•5mo ago

what do you mean?

BlackwolfOP•5mo ago

i read the full table into an array, and tried to change THAT array

ἔρως•5mo ago

yup, therefore my answer you just need to read the data you need, and you get what you want it's also a lot more performant

BlackwolfOP•5mo ago

i needed all the data initially though to analyse something first. I just need to revisit the table

ἔρως•5mo ago

do you still need all the data?

BlackwolfOP•5mo ago

not after analysing it, no, which was why i just wanted to either remove the fields i did not need, or make a new array with what i did but easier to re-read the table having said that, it would be useful to know how to make a new array from an existing one another time i might need firstnames and age

ἔρως•5mo ago

you have 2 options: for or array_map

BlackwolfOP•5mo ago

my preference would be the one with the least code 😄

ἔρως•5mo ago

for:

for($i = 0, $len = count($array); $i > $len; $i++) {
  $array[$i] = [
    'firstname' => $array[$i]['firstname'],
    'lastname' => $array[$i]['lastname'],
  ];
}

for($i = 0, $len = count($array); $i > $len; $i++) {
  $array[$i] = [
    'firstname' => $array[$i]['firstname'],
    'lastname' => $array[$i]['lastname'],
  ];
}

array_map:

$array = array_map(fn($item) => [
  'firstname' => $item['firstname'],
  'lastname' => $item['lastname'],
], $array);

$array = array_map(fn($item) => [
  'firstname' => $item['firstname'],
  'lastname' => $item['lastname'],
], $array);

BlackwolfOP•5mo ago

wow, that seems very straight forward

ἔρως•5mo ago

it's way easier than it feels like

BlackwolfOP•5mo ago

that worked perfectly @ array_map i shall make a note of both though, thank you very much 🙂

ἔρως•5mo ago

you're welcome this should save re-reading from the database

BlackwolfOP•5mo ago

indeed ... now i shall take a well earned break and drink a bucket of coffee 😄

ἔρως•5mo ago

i would skip on the bucket of coffee, at this time

BlackwolfOP•5mo ago

it's only 21:20 here 7hours till bedtime

ἔρως•5mo ago

terrible time to drink coffee

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How do I make an array from specific keys in another array?