array python to php

Question

I have to translate a python code to php, but I don't know how this python code work in php :

dec = data_ar[4:len(data_ar)]

I don't know what's the colon ":" between [ ]! Thanks

Your Python code could be improved: `data_ar[4:]` – DaoWen Mar 20 '13 at 21:35 — DaoWen, Mar 20 '13 at 21:35
But colon is not used in the same case in php... – user2188438 Mar 20 '13 at 21:37 — user2188438, Mar 20 '13 at 21:37

score 3 · Accepted Answer · edited May 23 '17 at 12:21

3

That's just Python's array slicing notation, so I think what you want is array_slice:

array_slice($data_ar, 4);

edited May 23 '17 at 12:21

Community

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answered Mar 20 '13 at 21:35

DaoWen

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Joshua Burns · Answer 2 · 2013-03-21T14:46:16.243

3

If you're trying to achieve the exact functionality in PHP:

<?php
$data_ar = array(1,2,3,4,5,6,7);
$dec = array_slice($data_ar, 4, count($data_ar)-4);

Now, the interesting thing here is the len(data_ar). If you provide the colon without a second argument, "until the end" is assumed. So this piece of functionality should actually have been written like so:

dec = data_ar[4:]

Likewise, we can modify the PHP side of things to reflect the same simplicity:

<?php
$data_ar = array(1,2,3,4,5,6,7);
$dec = array_slice($data_ar, 4);
print_r($dec); // Returns array(5,6,7)

edited Mar 21 '13 at 14:46

answered Mar 20 '13 at 21:37

Joshua Burns

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As with his Python example, there's no need to recompute the length. `array_slice` goes to the end of the array by default. (Check the documentation.) – DaoWen Mar 20 '13 at 21:38
+1 for using [`print_r`](http://www.php.net/manual/en/function.print-r.php). Knowing about that function will probably help him a lot with debugging. – DaoWen Mar 20 '13 at 21:42
I just read your explanation and decided to (temporarily) change my +1 to -1 since this is wrong: _Offsets start at zero, so they're actually grabbing one more than the length of the list._ Read the link in my answer on Python array slicing and fix your answer. When you've fixed it I'll give back the +1! – DaoWen Mar 20 '13 at 21:44
i think maybe you're mis-understanding something here. are you a python programmer yourself? if `mystr = 'hiho'` and you print `mystr[1:]` `iho` is printed. nothing about my statement is incorrect. – Joshua Burns Mar 20 '13 at 21:53
@JoshuaBurns - I don't use Python much, but I know enough to know that your statement about going off the end of the list is wrong. As with a lot of other slicing functions, the first index arg is _inclusive_ and the second is _exclusive_. I.e. you _must_ specify an index that's one _after_ the last element you want. – DaoWen Mar 21 '13 at 00:03

score 0 · Answer 3 · answered Mar 20 '13 at 21:35

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Colon means "to" in most languages. This means index 4 to the length of the array (the end).

In PHP, you can use array_slice like this:

$dec = array_slice($data_ar, 4)

answered Mar 20 '13 at 21:35

Christian Stewart

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array python to php

3 Answers3