Is it possible to convert from numeric to an alphanumeric code like this:
a
b
c
d
..
z
1
2
3
4
..
aa
ab
ac
ad
..
az
a1
a2
a3
a4
..
aaa
aab
aac
aad
..
aaz
aa1
aa2
etc.
I'm trying to convert large numbers to smaller length alphanumeric strings.
Don't know why you want to do this specifically, but try changing the base from 10 to something like 32;
base_convert($number, 10, 32);
Then to convert back
base_convert($number, 32, 10);
As someone else pointed out - for very large numbers this may not work.
If you need to be able to handle very large numbers, check out this link:
How to generate random 64-bit value as decimal string in PHP
You can use base_convert() for changing the base of your number from 10 (decimal) to 36 (26 latin letters plus 10 arabic numerals).
The result will differ from your given example list. You have used the digits abc..xyz012..789, base_convert will use a diffent order 012..789abc..xyz.
// convert decimal to base36
echo base_convert($number_dec, 10 , 36);
// convert base36 to decimal
echo base_convert($number_b36, 36 , 10);
Translation
dec base36
0 0
1 1
...
9 9
10 a
11 b
...
34 y
35 z
36 10
37 11
..
45 19
46 1a
...
1295 zz
1296 100
1297 101
You could use dechex to convert the number to hex
http://php.net/manual/en/function.dechex.php
For example:
1000000 => f4240
1000001 => f4241
1000002 => f4242
1000003 => f4243
1000004 => f4244
1000005 => f4245
1000006 => f4246
1000007 => f4247
1000008 => f4248
1000009 => f4249
1000010 => f424a
1000011 => f424b
1000012 => f424c
1000013 => f424d
1000014 => f424e
1000015 => f424f
1000016 => f4250
1000017 => f4251
1000018 => f4252
1000019 => f4253
1000020 => f4254
To convert back, just use hexdec
http://php.net/manual/en/function.hexdec.php
base64_encode();
and for decode use
base64_decode();
Both dechex() and base_convert() will fail with large numbers. They are limited by the maximum size and precision of int and float types internally used during conversion.
The http://php.net/manual/pt_BR/function.base-convert.php discussion has some nice helper functions (see 2, 3) that can avoid this problem by using BC-functions to do the math. The BC extension can deal with arbitrarily large numbers.
Related
Im doing a Grib2 decoder in PHP, and started with a half written library that I found. Everything is working fine except the values I get from the data are incorrect after converting Int Values to real values. I think I am converting everything right, and even when I test with cloud data it looks correct when I check it in Panoply. I think its with this formula that is all over the internet. Below im using 10 m above ground GFS from https://nomads.ncep.noaa.gov
Y*10^D = R+(X1+X2)*2^E
Im not sure I'm plugging in the values correctly but again it works with cloud cover percentages.
So.... The "Data Representation Values" I get from Grib Section 5
'Reference value (R)' => 886.25067138671875,
'Binary Scale Factor (E)' => 0,
'Decimal Scale Factor (D)' => 2,
'Number of bits used for each packed value' => 11,
'exp' => pow(2, $E), //(Equals 1) (The Library used these as the 2^E)
'base' => pow(10, $D), //(Equals 100) (And the 10^D)
'template' => 0,
As you can see below the numbers definitely have a connection to the Reference Value. The Number closest to 886(R) is 892 and its actual value should be 0.05 as shown below (EX.) The numbers Higher are than 892 are positive and the ones lower than 892 are negative. But when I user the formula (886 + 892 * 1) / 100 it give me 17.78, not 0.05. I seem to be missing something pretty obvious, am I misunderstanding the formula/equation where Y is the value I want...
X1 = 0 (documentation says)
X2 = 892 (documentation says is scaled value, the value in the Grib from bits?)
2^0 = 1
10^2 = 100
R = 886.25067138671875
Y * 10^D = R + (X1 + X2) * 2^E
Y * 100 = R + (X1 + X2) * 1
886 + (0 + 892) * 1 ) / 100
(886 + 892 * 1) / 100
= 17.78
Int Values of wind from Grib (After converting from Bits)
0 => 695,
1 => 639,
2 => 631,
3 => 0,
4 => 436,
5 => 513,
6 => 690,
7 => 570,
8 => 625,
9 => 805,
10 => 892,<-----------(EX.)
11 => 1044,
12 => 952,
13 => 1081,
14 => 1414,
15 => 997,
16 => 1106,
17 => 974,
18 => 1135,
19 => 1069,
20 => 912,
Actual decoded wind values shown in Panoply (Well known Grib App)
-1.9125067
-2.4725068
-2.5525067
-8.862507
-4.5025067
-3.7325068
-1.9625068
-3.1625068
-2.6125066
-0.81250674
0.057493284 <-----------(EX.)
1.5774933
0.6574933
1.9474933
5.2774935
1.1074933
2.1974933
0.87749326
2.4874933
1.8274933
0.2574933
y = 0.01 * (x - 886.25067138671875) seems to work for all points
so 0.01 * (892 - 886.25067138671875) = 0.0574
This question already has an answer here:
PHP, sort, sort_flags
(1 answer)
Closed 2 years ago.
I have an array to sort as
$numbers = array(24, 19, 3, 16, 56, 8, 171);
sort($numbers, SORT_STRING);
print_r($numbers);
And thus when i sort the array i get the result as
(
[0] => 16
[1] => 171
[2] => 19
[3] => 24
[4] => 3
[5] => 56
[6] => 8
)
How does the SORT_STRING works can anybody explain it to me?
SORT_STRING will compare character by character as in a word. So letter A is "higher" (or lower, your choice) than B, B > C.
1 > 2, 2 > 3, 11 > 12 and so on.
So in your case, when comparing 24 with 19, it will compare 1 with 2 and then order.
As a second example, when comparing 19 with 16, first will compare 1 with 1, which is equal, then compare 9 with 6, making 6 (and 16) a higher order.
More info here: PHP, sort, sort_flags
If you want to dig deeper, this is the link for the PHP source code.
This is the line where it choices the sort algorithm depending on the sort flag:
https://github.com/php/php-src/blob/50765075db6b6d5a9597589601c59f743f6ee9c8/ext/standard/array.c#L502
And here where it execute the comparison/sort:
https://github.com/php/php-src/blob/50765075db6b6d5a9597589601c59f743f6ee9c8/ext/standard/array.c#L207
And then it will call a zend operator:
https://github.com/php/php-src/blob/5430a466ff31422b436df076581d8345531db975/Zend/zend_operators.c
The SORT_STRING compare items as strings. You can find more detail here: https://www.php.net/manual/en/function.sort.php
A simple example is when you sort your files or directories on you computer: the sorting is alphabetical order.
This works as an ascending numeric values for the first digits(as 1 in 16) of all the numbers and after finishing them all,the pointer goes towards the digit next to it (as 6 in 16) and this is how it works so basically it arranges the digits from the left most digit and then goes on arranging them by the preceeding ones(right).
For example: comparing between 16 and 171
As both the numbers have their left-most digits as 1 it sorts it numbers based on their next digits(the right ones).
And thus by following the rule you get an result array as
(
[0] => 16
[1] => 171
[2] => 19
[3] => 24
[4] => 3
[5] => 56
[6] => 8
)
I'm having a hard time to figure out, how to format a range of number correctly.
Lets say I have an array with the following values:
array( 1, 2, 001, 02, 012 );
How can I change the output of each value to fit the following format?
0 => 1
1 => 2
2 => 0.01
3 => 0.2
4 => 0.12
I'm not looking for a loop ( this is just for explanation), just a way to format the number correctly.
This is the way PHP interpret Integer you can see you have no leading zeros on Integer ;-)
var_dump(array( 1, 2, 001, 02, 012 ));
array(5) {
[0]=>int(1)
[1]=>int(2)
[2]=>int(1)
[3]=>int(2)
[4]=>int(10)
}
The only way to solve it is converting it to a String.
I am facing a problem i am not capable to solve. I have a string consisting of not needed text and 10 digit numbers who always start with "2" or "6". I need to get those in 10digit numbers into an array. I thought of regex and found this article Regular Expression for matching a numeric sequence? which is pretty close to what i need (except the descending/ascending thing) yet, as i could never and will NEVER be able to understand regex, i cant modify to my needs. If anyone could help me out here i would highly appreciate it!
Here is a sample of my string:
".........693 7098469 - ZQH X Bop. Hrtepou 50 flerpoUrroXn ........210 5014166 - 0E000PA E KapaoAn Anpn-rPou 21
EAArivtg .....................................................210 9618677 - MAPIA KapaoAri Arpn-rptou 21 Elanvolo .. 210 9643623 - MAPIA E ...................................................... 210 9643887 - MAPIA 0 loucrrivou 8 HX.toOrran ..............210 9914534 AIPITAKHE APTEMIOE n Avrtnopou 22
Reptcrrept ....._.........._......._................697 7440896 , -10AN."
Thank you very much in advance!
Greetings from Greece!
As I see your string your digits have an space between, and if you want strictly make your selections this is the regex:
[62]\d{2}\s*\d{7}
Explanation:
[62] # Start with 6 or 2
\d{2} # 2 more digits
\s* # any number of white spaces
\d{7} # 7 more digits
Live demo
and PHP code which has preg_match_all to match all occurrences of those strings:
preg_match_all("/[62]\d{2}\s*\d{7}/", $text, $matches);
Output:
Array
(
[0] => 693 7098469
[1] => 210 5014166
[2] => 210 9618677
[3] => 210 9643623
[4] => 210 9643887
[5] => 210 9914534
[6] => 697 7440896
)
PHP live demo
Maybe like this:
<?php
$x=
".........693 7098469 - ZQH X Bop. Hrtepou 50 flerpoUrroXn ........210 5014166 - 0E000PA E KapaoAn Anpn-rPou 21 EAArivtg ....................................................210 9618677 - MAPIA KapaoAri Arpn-rptou 21 Elanvolo .. 210 9643623 - MAPIA E ...................................................... 210 9643887 - MAPIA 0 loucrrivou 8 HX.toOrran ..............210 9914534 AIPITAKHE APTEMIOE n Avrtnopou 22
Reptcrrept ....._.........._......._................697 7440896 , -10AN.";
$x=str_replace(' ','',$x);
preg_match_all('/((2|6)\d{9})/',$x,$matches);
print_r($matches[0]);
And the result:
Array
(
[0] => 6937098469
[1] => 2105014166
[2] => 2109618677
[3] => 2109643623
[4] => 2109643887
[5] => 2109914534
[6] => 6977440896
)
there is a pretty cool page, that visualize the regex code for better understading:
https://www.debuggex.com/
this should work
((?:2|6)[0-9]{2} [0-9]{7})
I have an array:
$test =array('49'=> '-0','51'=> '-0','50'=> '0','53'=> '-1.69','55'=> '0','57'=> '-2','59'=> '-6','60'=> '-12','65'=> '0','66'=> '0','67'=> '21.69','69'=> '0','70'=> '0','71'=> '0',);
echo "\n".'===== First Method ========';
echo "\n\n".print_r($test);
echo "\n array_sum: ".array_sum($test);
echo "\n\n".'===== Second Method ========';
$total = 0;foreach($test as $value) $total += $value;
echo "\n foreach:".$total."\n";
the result is
gd#gd:~/Desktop$ php test.php
===== First Method ========Array
(
[49] => -0
[51] => -0
[50] => 0
[53] => -1.69
[55] => 0
[57] => -2
[59] => -6
[60] => -12
[65] => 0
[66] => 0
[67] => 21.69
[69] => 0
[70] => 0
[71] => 0
)
1
array_sum: 3.5527136788005E-15
===== Second Method ========
foreach:3.5527136788005E-15
it is wrong, the result should be 0, not 3.5527136788E-15, how to fix it ?
This is just your standard floating point arithmetic precision error.
php -r "echo -1.69 + -2 + -6 + -12 +21.69;"
3.5527136788005E-15%
You can fix it by using ints rather than floats. For example, if you always expect 2 digits of precision, multiply all your numbers by 100, round them off to ints, sum them, and divide by 100.
php -r "echo (-169 + -200 -1200 +2169 + -600) / 100;"
0%
You are doing array_sum with strings. Remove the quotes on the values, or covert them to integers before using array_sum - I imagine it is converting the strings to integers incorrectly - only on my phone so can't check specifics.
Hope this helps.
Why not just give the values as floating point numbers rather than enclosing them in quotes. That would basically make it a string summation and strange result is expected. I think in before PHP version 4.something it used to convert the string to numbers. It might especially be problem with decimal numbers.
This is just an example of floating point imprecision. It's impossible to represent .69 exactly in binary (much like it's impossible to represent 1/3 exactly in decimal).
If you need exact numbers, you can look into using the bcmath php extension.