PHP get key value pairs out from an array within a new array (array filtering, array reducing)

Question

I am having an associative array like this:

[1] => Array
        (
            [logo] => 
            [starting] => 
            [prelim_info] => 
            [state_entry] => 1
            [district_entry] => 3
            [CLIx_code] => 1009
            [survey_time] => 2017-05-29 09:38:00.0
            [Implement_module] => 
            [CLIxModule_Impl] => 1
            [Noimplement_reason] => 
            [Other_Reason] => 
            [implementedModule_Name] => 7 10 11 12
            [Lab_Open] => 3
            [Lab_Management] => 1
            [Planned_CLIxPeriods] => 2
            [ReasonsCancellation_CLIxClass] => 5
            [PowerCut_Visit] => 2
            [Observe_session:Session_observe] => 2
            [Observe_session:grade_observe] => 
            [Observe_session:grade_other] => 
            [Observe_session:Module_Observed] => 
            [Observe_session:Unit_Observed] => 
            [Observe_session:Lesson_Observed] => 
            [Observe_session:time_Sufficient] => 
            [Observe_session:Student_workindependent] => 
            [Observe_session:groupsinteracting] => 
            [Observe_session:groupshelping] => 
            [Observe_session:Students_Mothertongue] => 
            [Observe_session:Students_handbook] => 
            [Observe_session:Students_reflections] => 
            [Observe_session:teacherpresent] => 
            [Observe_session:encourage_platform] => 
            [Observe_session:encourage_classdisc] => 
            [Observe_session:mothertongue_teacher] => 
            [Observe_session:teacher_handbook] => 
            [Observe_session:Teacher_prepared] => 
            [TPDcertification_support1:TPD_Cert_Subject1] => 
            [TPDcertification_support1:tchrSupport_TPD1] => 
            [TPDcertification_support1:Source_Support] => 
            [TPDcertification_support2:TPD_Cert_Subject2] => 
            [TPDcertification_support2:tchrSupport_TPD2] => 
            [TPDcertification_support2:Source_Support] => 
            [TPDcertification_support3:TPD_Cert_Subject] => 
            [TPDcertification_support3:tchrSupport_TPD3] => 
            [TPDcertification_support3:Source_Support] => 
            [TPDcertification_support4:TPD_Cert_Subject] => 
            [TPDcertification_support4:tchrSupport_TPD4] => 
            [TPDcertification_support4:Source_Support] => 
            [teacher_feedback] => Regarding the old modules, maths teachers said that it was very useful as well as workbook.
            [FSP_feedback] => NA
            [TPDsuppport_certification:Supt_TPDcertification] => 1
            [TPDsuppport_certification:Source_Supportcertification] => 4
            [teacherSupport_moduleImplement] => They had training organised by the clix team and RMSA.
            [HighPoint] => NA
            [LowPoint] => There was no clix class since school reopen.
            [schlcontact_FSP_nooftimes] => 0
            [FT_contactreason] => 5
            [FT_otherreason] => 
            [Support_fromTE] => 2
            [Action_FT] => 1
            [Specific_ActionFT] => School lab need to recheck for start rolling out the modules.
            [Action_CLIxTeam] => 2
            [Sepecific_ActionCLIx] => 
            [Action_State] => 1
            [Specific_ActionState] => To issue the class period include in their regular time table.
            [Action_TPD] => 2
            [Specific_ActionTPD] => 
            [Session_observe2:Module_Second] => 
            [Session_observe2:Observe_grade] => 
            [Session_observe2:other_grade] => 
            [Session_observe2:Observation_Module2] => 
            [Session_observe2:Observation_Unit2] => 
            [Session_observe2:Observation_Lesson2] => 
            [Session_observe2:time_Sufficient2] => 
            [Session_observe2:Student_workindependent2] => 
            [Session_observe2:groupsinteracting2] => 
            [Session_observe2:groupshelping2] => 
            [Session_observe2:Students_Mothertongue2] => 
            [Session_observe2:Students_handbook2] => 
            [Session_observe2:Students_reflections2] => 
            [Session_observe2:teacherpresent2] => 
            [Session_observe2:encourage_platform2] => 
            [Session_observe2:encourage_classdisc2] => 
            [Session_observe2:mothertongue_teacher2] => 
            [Session_observe2:teacher_handbook2] => 
            [Session_observe2:Teacher_prepared2] => 
            [teacher_feedback2] => 
            [FSP_feedback2] => 
            [TPD_certification:tcher_TPD] => 
            [TPD_certification:certification_course_tchr_suport] => 
            [teachersupport_moduleImplement2] => 
            [school_location:Latitude] => 23.7428370300
            [school_location:Longitude] => 92.7227306900
            [school_location:Altitude] => 1014.0000000000
            [school_location:Accuracy] => 18.0000000000
            [generated_note_name_110] => 
            [meta:instanceID] => uuid:2568400e-0ec3-421d-94bc-10653732e6d2
        )

I want some key-value pairs from this array for data analysis and visualization. the output should look something like this:-

array(
    [CLIx_code] => 1009
    [state_entry] => 1
    [district_entry] => 3
    ...
)

Basically, I want an array with a few key value pairs filtered on which I can operate some mathematical functions and pass those to D3.js for data visualization.

I tried it this way:

for ($i=0;$i<count($all_rows);$i++){
    $filteredarray[] = array($all_rows[$i]['CLIx_code'], $all_rows[$i]['state_entry'], $all_rows[$i]['district_entry']);    
}`

But I want key value pairs not only the value I even tried using array_filter().

Answer 1

I have to assume you know the key names for the elements that you want to retain and run calculations on, so array_intersect_key() is the right tool for the job.

Code (Demo):

$array=[
    'logo'=>'', 
    'starting'=>'', 
    'prelim_info'=>'', 
    'state_entry'=>1,
    'district_entry'=>3,
    'CLIx_code'=>1009
    // ... more elements
];
$filterkeys=[
    'state_entry',
    'district_entry',
    'CLIx_code'
    // ... more key names
];
var_export(array_intersect_key($array,array_flip($filterkeys)));

Output:

array (
  'state_entry' => 1,
  'district_entry' => 3,
  'CLIx_code' => 1009,
)

---

Alternatively, you can drop the array_flip() call if you set your $filterkeys key names as keys, like this:

$filterkeys=[
    'state_entry'=>'',
    'district_entry'=>'',
    'CLIx_code'=>''
    // ... more key names
];
var_export(array_intersect_key($array,$filterkeys));

Answer 2

PHP: How to use array_filter() to filter array keys?

Just refer this Question's answer Like in your case you need to write some code like below:-

<?php
//You have below array including all keys
$result_array = array('logo'=>'test','state_id'=>125,'prelim_info'=>'','CLIxModule_Impl'=>'5','district_entry'=>3);

// Now provide only those keys which you need to filter.
$filter_keys = array('district_entry','state_id');

$filtered_array = array_filter($result_array,
    function ($key) use ($filter_keys) {
        return in_array($key, $filter_keys);
    },
    ARRAY_FILTER_USE_KEY
);
var_dump($filtered_array);

?>