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php – How to get the number of columns of worksheet as integer (28) instead of Excel-letters ("AB")?

Posted by: admin April 23, 2020 Leave a comment

Questions:

Given:

$this->objPHPExcelReader = PHPExcel_IOFactory::createReaderForFile($this->config['file']);
$this->objPHPExcelReader->setLoadSheetsOnly(array($this->config['worksheet']));
$this->objPHPExcelReader->setReadDataOnly(true);
$this->objPHPExcel = $this->objPHPExcelReader->load($this->config['file']);

I can iterate through the rows like this but it is very slow, i.e. in a 3MB Excel file with a worksheet that has “EL” columns, it takes about 1 second per row:

foreach ($this->objPHPExcel->setActiveSheetIndex(0)->getRowIterator() as $row)
{
    $dataset = array();
    $cellIterator = $row->getCellIterator();
    $cellIterator->setIterateOnlyExistingCells(false);
    foreach ($cellIterator as $cell)
    {
        if (!is_null($cell))
        {
            $dataset[] = $cell->getCalculatedValue();
        }
    }
    $this->datasets[] = $dataset;
}

When I iterate like this, it it significantly faster (approx. 2000 rows in 30 seconds), but I will have to convert the letters e.g. “EL” to a number:

$highestColumm = $this->objPHPExcel->setActiveSheetIndex(0)->getHighestColumn(); // e.g. "EL"
$highestRow = $this->objPHPExcel->setActiveSheetIndex(0)->getHighestRow();

$number_of_columns = 150; // TODO: figure out how to get the number of cols as int
for ($row = 1; $row < $highestRow + 1; $row++) {
    $dataset = array();
    for ($column = 0; $column < $number_of_columns; $column++) {
        $dataset[] = $this->objPHPExcel->setActiveSheetIndex(0)->getCellByColumnAndRow($column, $row)->getValue();
    }
    $this->datasets[] = $dataset;
}

Is there a way to get the highest column as an integer (e.g. “28”) instead of in Excel-styled letters (e.g. “AB”)?

How to&Answers:
$colNumber = PHPExcel_Cell::columnIndexFromString($colString);

returns 1 from a $colString of ‘A’, 26 from ‘Z’, 27 from ‘AA’, etc.

and the (almost) reverse

$colString = PHPExcel_Cell::stringFromColumnIndex($colNumber);

returns ‘A’ from a $colNumber of 0, ‘Z’ from 25, ‘AA’ from 26, etc.

EDIT

A couple of useful tricks:

There is a toArray() method for the worksheet class:

$this->datasets = $this->objPHPExcel->setActiveSheetIndex(0)->toArray();

which accepts the following parameters:

* @param  mixed    $nullValue          Value returned in the array entry if a cell doesn't exist
* @param  boolean  $calculateFormulas  Should formulas be calculated?
* @param  boolean  $formatData         Should formatting be applied to cell values?
* @param  boolean  $returnCellRef      False - Return a simple array of rows and columns indexed by number counting from zero
*                                      True - Return rows and columns indexed by their actual row and column IDs

although it does use the iterators, so would be slightly slower

OR

Take advantage of PHP’s ability to increment character strings Perl Style

$highestColumm = $this->objPHPExcel->setActiveSheetIndex(0)->getHighestColumn(); // e.g. "EL" 
$highestRow = $this->objPHPExcel->setActiveSheetIndex(0)->getHighestRow();  

$highestColumm++;
for ($row = 1; $row < $highestRow + 1; $row++) {     
    $dataset = array();     
    for ($column = 'A'; $column != $highestColumm; $column++) {
        $dataset[] = $this->objPHPExcel->setActiveSheetIndex(0)->getCell($column . $row)->getValue();
    }
    $this->datasets[] = $dataset;
}

and if you’re processing a large number of rows, you might actually notice the performance improvement of ++$row over $row++

Answer:

Not sure if your class has a built in method, but you could always use the ord() function on each letter of the column index string. You will of course have to subtract out the base value of ‘A’, and multiply by 26^x for each position from the far right of the string. Something like:

    $input_string = 'BC';
    $base_value = 64;
    $decimal_value = 26;
    $column_index = 0;
    for ($i = 0; $i < strlen($input_string); $i++) {
        $char_value = ord($input_string[$i]);
        $char_value -= $base_value;
        $char_value *= pow($decimal_value, (strlen($input_string) - ($i + 1)));
        $column_index += $char_value;
    }
    echo $column_index;

Basically this would make ‘BC’ equal (2 * 26^1) + (3 * 26^0) = 55.

$input_string being the column index string, $base_value being the ord() value of ‘A’ minus 1, and $decimal_value being the value of A0. Should work up to any number column. Have tested. Hope this helps.

Answer:

This is a somewhat simplified version of dqhendricks answer. I have added to copies, one function assuming you enter the full excel cell reference (ie. “AB12”) and the other assuming you enter just the column reference (ie. “AB”). They both return a zero based index.

Input Full Cell Reference

function getIndex ($cell) {
    // Strip cell reference down to just letters
    $let = preg_replace('/[^A-Z]/', '', $cell);

    // Iterate through each letter, starting at the back to increment the value
    for ($num = 0, $i = 0; $let != ''; $let = substr($let, 0, -1), $i++)
        $num += (ord(substr($let, -1)) - 65) * pow(26, $i);

    return $num;
}

Input Column Reference Only

function getIndex ($let) {
    // Iterate through each letter, starting at the back to increment the value
    for ($num = 0, $i = 0; $let != ''; $let = substr($let, 0, -1), $i++)
        $num += (ord(substr($let, -1)) - 65) * pow(26, $i);

    return $num;
}

The function goes from the back of the string to the front to increase the value of the column. It uses the ord() function to get the numeric value of a character and then has the letter value subtracted to give the local column value. Finally it is multiplied by the current power of 26.

Answer:

I suggest to convert excel to array, clean it from empty elements and then count the number of columns:

protected function getColumnsCheck($file, $col_number) {
        if (strstr($file, ".xls") != false && strstr($file, ".xlsx") != false) {
            $fileType = PHPExcel_IOFactory::identify($file);
            $objReader = PHPExcel_IOFactory::createReader($fileType);
            $objPHPExcel = $objReader->load($file);
            $columns_empty = $objPHPExcel->getActiveSheet(0)->toArray()[0]; 

            $columns = array_filter($columns_empty);

            return ($col_number==count($columns));
        }
        return false;
    }

Answer:

    function getNameFromNumber($num) {//(Example 0 = A, 1 = B)
$numeric = $num % 26;
$letter = chr(65 + $numeric);
$num2 = intval($num / 26);
if ($num2 > 0) {
    return getNameFromNumber($num2 - 1) . $letter;
} else {
    return $letter;
}
}

getNameFromNumber(0) //return A

Answer:

/**
 * 
 */
function number_to_alphabet($number) {
    $number = intval($number);
    if ($number <= 0) {
        return '';
    }
    $alphabet = '';
    while($number != 0) {
        $p = ($number - 1) % 26;
        $number = intval(($number - $p) / 26);
        $alphabet = chr(65 + $p) . $alphabet;
    }
    return $alphabet;
}

/**
 * Required PHP 5.6.
 * @see: http://php.net/manual/en/language.operators.arithmetic.php
 */
function alphabet_to_number($string) {
    $string = strtoupper($string);
    $length = strlen($string);
    $number = 0;
    $level = 1;
    while ($length >= $level ) {
        $char = $string[$length - $level];
        $c = ord($char) - 64;        
        $number += $c * (26 ** ($level-1));
        $level++;
    }
    return $number;
}

Test:

for ($x=1; $x<=1000; $x++) {
    echo 'number_to_alphabet('.$x.') = ',$y = number_to_alphabet($x),'; ';
    echo 'alphabet_to_number('.$y.') = '.alphabet_to_number($y).'; ';
    echo PHP_EOL;
}