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PHP classes and helpers that might be helpful when working with data files, variable name lists, etc.

Data\Helper provides some static helper functions

Usage

<?php
require '/path/to/vendor/autoload.php';

use Fiedsch\Data\Helper;
use Fiedsch\Data\Listmanager;
use Fiedsch\Data\ArrayRecordCreator;

// use Helper::expandExpression() et al.
// use Listmanager to perform operations on lists (arrays)
// use ArrayRecordCreator to create data records
// use Helper::columnIndex() and Helper::columnName() for column name to numerical index mappings

Examples

Create a list of variable names

Create a list of variable names that might make it easier to write code in your favourite software for statistical analysis.

print Helper::getExpression('a001', 'a111');
// 'a{001,111}'

Helper::expandExpression('a{001,111}');
// array('a001', 'a002', 'a003', ..., 'a099', 'a100', ..., 'a111')

print "someFunction(" . join(',', Helper::expandExpression('a{001,101}')) . ");";

Create a list of file names

Helper::expandExpression('image{00001,00099}.jpg');
// array('image00001.jpg', ..., 'image00099.jpg')

Comparing Lists

Notice: result are a lists, not sets (see e.g. union()!)

$listA = ['a','b','c'];
$listB = ['c','d','e'];
$manager = new Listmanager($listA);
$result = $manager->without($listB);   // ['a', 'b']
$result = $manager->intersect($listB); // ['c']
$result = $manager->union($listB);     // ['a','b','c','c','d','e']

$manager = new Listmanager(['a','b','c','c','b']);
$result = $manager->unique(); // ['a','b','c']

// find duplicates in a list
$list = ['a','b','a','a','c'];
$manager = new Listmanager($list);
$result = $manager->duplicates(); // ['a','a']
// $list[0] is considered unique, $list[2] and $list[3] are in the result

Creating data records

$creator = new ArrayRecordCreator(['foo','bar','baz']);
 // add values in arbitrary order
 $creator->foo = '1';
 $creator->baz = '2';
 $creator->bar = '3';
 $record = $creator->getRecord(); // [1, 3, 2]

 $creator->reset();
 $creator->foo = 'FOO';
 $record = $creator->getRecord(); // ['FOO', null, null]

Combined usage with Helper

 // create target columns 'col001' to 'col100'
 $creator = new ArrayRecordCreator(Helper::expandExpression('col{001,100}'));
 $creator->col042 = 'fourtytwo';
 // ...

Working with data arrays read from a (CSV) file

If you are working with data records stored in PHP arrays--e.g. when reading lines from a CSV file--you might find it useful to access the entries by their "column name" rather than their numerical index. This is especially useful if the data originally "lives" in an Excel Spreadsheet where you have column names "A", "B", ...

To map "A", "B", ... to the respective array indices 0, 1, ... you can use

Helper::columnIndex("A"); // 0
Helper::columnIndex("B"); // 1
// ...
Helper::columnIndex("AQ"); // 42

The inverse funtion to columnIndex() is columnName() which might also be useful when dealing with column name to array index mappings.

Helper::columnName(0); // "A"
Helper::columnName(1); // "B"
// ...
Helper::columnName(42); // "AQ"

Working with column name mappings

Assume, you have an array that maps (some) variable names to column names:

['one'=>'A', 'two'=>'C', 'three'=>'X']

(with "some" meaning that the mapping does not have to be continous).

Now, if you prepend new columns in a data management step you need to adapt the mapping for the next step to match the new data:

Helper::prependAndRemap(['one'=>'A', 'two'=>'C', 'three'=>'X'], ['four', 'five'])
// ['four'=>'A', 'five'=>'B', 'one'=>'C', 'two'=>'E', 'three'=>'Z']

Working with wave specifications

Experimental: might change in future versions!

Consider a survey that is conducted 12 times a year. We call "these waves" something like '01-2023', '02-2023', ..., '12-2023'.

When we want to access the name of a wave "tree waves back", we want to move from '08-2023' to '05-2023' for example, but '02-2023'to'11-2022'` should also be computed correctly.

Helper::moveWave('08-2023', -3); // '05-2023'
Helper::moveWave('02-2023', -3); // '11-2023'
Helper::moveWave('10-2023', +3); // '01-2024'

Use a different pattern like so:

Helper::moveWave('09/2023', -3, '(\d{2})(\/)(\d{4})', Helper::ORDER_WAVE_FIRST); // '06/2023'
Helper::moveWave('2023/09', -3, '(\d{4})(\/)(\d{2})', Helper::ORDER_WAVE_LAST);  // '2023/06'

fiedsch / data_util

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