json_decode is rounding floats, how can I prevent it?

Question

I have a rather big json file with coordinates in the following format

"[[3.2,1],[4.8,2]]"

which represents (3.2,1) and (4.8,2)

I'm using these coördinates to generate a D3 geographic map, but when php is modelling this information into a geoJSONobject I encounter the following error:

I need to transform the coordinates into a array for which I use json_decode. However:

json_decode("[[3.2,1],[4.8,2]]")

returns

Array
(
[0] => Array
    (
        [0] => 3
        [1] => 1
    )
[1] => Array
    (
        [0] => 4
        [1] => 2
    )
)

Where I lose the decimals. How can I prevent this?

Edit:

{"type": "FeatureCollection",
 "features": [{
        "type": "Feature",
        "geometry": {
            "type": "Polygon",
            "coordinates": "[[[8.7, 11], [8.89, 12.13],[9.27, 12.13], [9.9, 12], [9.7, 10.8], [8.7, 11]]]"
        },
        "properties": {
            "name": "04",
            "count": "25"
        }
    }]
}

This is an example of the data I'm getting as output. (It is supposed to represent a map of rooms which are get a density color by its usage)

I am able to parse this using jQuery.parseJSON(data), but running the following D3 code generates the weirdest errors:

val(svgname).append("g")
    .selectAll("path")
    .data(geoJSONobject.features)
    .enter().append("path")
    .attr("d", path)
    ...

error I think it's because of the quotes around the array of coordinates.

Edit (2) - actual solution

The solution I accepted was a workaround, but the true issue was localized php-settings. using:

echo json_encode($dataset, JSON_NUMERIC_CHECK);

in the php-file, all the issues were resolved. Though I'd update the question since it is still being looked at (if anyone would encouter the issue)

what version of PHP are you using? I'm running 5.5.12 and it leaves them as floats. — Tom Jardine-McNamara, Jul 09 '15 at 14:35
I do not know what causes this, but maybe as a workaround: Pass them around as strings maybe, then cast them to floats when you receive the coordinates. — Erwin Moller, Jul 09 '15 at 14:39
The docs (http://php.net/json_decode) do mention casting large integers to floats, but yours don't look very large ;) @ErwinMoller's suggestion of using strings will absolutely work. Whether you're curious about *why* this is happening for you is another matter. — Tom Jardine-McNamara, Jul 09 '15 at 14:41
Looks good for `5.2.0 - 7.0.0alpha2` http://3v4l.org/rtamO#v520 `var_dump()` the var holding the JSON. — AbraCadaver, Jul 09 '15 at 14:50
I'm still using php 5.2.4, upgrading is sadly enough not possible... Is it possible to elaborate further on the passing around as strings method? — dietervdf, Jul 09 '15 at 15:41
It's real simple, he just means store them as strings and when you need to use them, convert them to floats. — Overcode, Jul 09 '15 at 16:11
Just wrap the values in quotes: `json_decode('[["3.2","1"],["4.8","2"]]');` — Travesty3, Jul 09 '15 at 16:13
Please provide a minimal example, as per the SO guidelines. Also, mixing in some jQuery claims doesn't help either to clarify the problem. — Ulrich Eckhardt, Jul 09 '15 at 16:43
The problem is solved by applying @Travesty3 s solution. I would gladly accept that solution if he would post it as an answer. — dietervdf, Jul 09 '15 at 17:12

score 9 · Answer 1 · edited May 23 '17 at 12:24

9

I had the same problem. I solved it using the followin regex

SOLUTION 1

$yourJsonVariable = preg_replace('/:\s*(\-?\d+(\.\d+)?([e|E][\-|\+]\d+)?)/', ': "$1"', $yourJsonVariable);

Convert it into array

$array = json_decode($yourJsonVariable, true);

Credits goes to this SO LINK

SOLUTION 2

You can set ini_set('precision',1);

SOLUTION 3

$decoded = json_decode($encoded, true, null, JSON_BIGINT_AS_STRING);

NOTE: The Last solution will work only for PHP > 5.4

You might want to take a look at this Blog

edited May 23 '17 at 12:24

Community

1
1

answered Jul 09 '15 at 16:23

Abhinav

8,028
12
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1

Should be marked as correct answer! Proposed as **Solution 1** worked for me like a charm – Ragen Dazs Nov 13 '17 at 12:39
After some tests, regex are matching numbers inside quotes ```/:\s*(?!\B"[^"]*)(\-?\d+(\.\d+)?([e|E][\-|\+]\d+)?)(?![^"]*"\B)/``` this condition will only quote numbers that are not already quoted – Ragen Dazs Nov 13 '17 at 12:59

score 0 · Accepted Answer · answered Jul 09 '15 at 19:45

0

Just wrap the values in quotes: json_decode('[["3.2","1"],["4.8","2"]]');

answered Jul 09 '15 at 19:45

Travesty3

14,351
6
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That's a workaround rather than a solution. It relies on dynamic typing in PHP and/or ECMAScript, where `"3.1"` and `3.1` are interpreted depending on the context. Formally, `"3.1"` in JSON is a string, while `3.1` is a floating-point type, and any JSON decoder worth its name should be able to decode it. – Ulrich Eckhardt Jul 09 '15 at 21:20
Well, I guess the solution would be to work with the lastest version of php. Since Tom Jenkins and others confirmed it to be working on their machines. Sadly enough I can't perform the upgrade. Meanwhile this *solved* my problem, which is why I marked it as *solution*. – dietervdf Jul 09 '15 at 22:00

json_decode is rounding floats, how can I prevent it?

Edit:

Edit (2) - actual solution

2 Answers2