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How to check if PHP array is associative or sequential?
...w to determine whether an array has sequential numeric keys, starting from 0
Consider which of these behaviours you actually need. (It may be that either will do for your purposes.)
The first question (simply checking that all keys are numeric) is answered well by Captain kurO.
For the second qu...
Relative frequencies / proportions with dplyr
...n = n()) %>%
mutate(freq = n / sum(n))
# am gear n freq
# 1 0 3 15 0.7894737
# 2 0 4 4 0.2105263
# 3 1 4 8 0.6153846
# 4 1 5 5 0.3846154
From the dplyr vignette:
When you group by multiple variables, each summary peels off one level of the grouping. That makes ...
Ruby: Merging variables in to a string
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answered Feb 16 '09 at 21:42
Mike WoodhouseMike Woodhouse
47.6k1212 gold badges8585 silver badges123123 bronze badges
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Check whether number is even or odd
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204
You can use the modulus operator, but that can be slow. If it's an integer, you can do:
if ( (...
Scrolling a flexbox with overflowing content
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answered Feb 4 '14 at 0:59
Joseph SilberJoseph Silber
184k4747 gold badges324324 silver badges265265 bronze badges
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do { … } while (0) — what is it good for? [duplicate]
I've been seeing that expression for over 10 years now. I've been trying to think what it's good for. Since I see it mostly in #defines, I assume it's good for inner scope variable declaration and for using breaks (instead of gotos.)
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How do I get the real .height() of a overflow: hidden or overflow: scroll div?
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Use the .scrollHeight property of the DOM node: $('#your_div')[0].scrollHeight
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How to sort an array in Bash
...ed and see!
– antak
Oct 19 '15 at 9:04
3
Very nice. Could you explain for the average bash user h...
What does value & 0xff do in Java?
... = value;
then result would end up with the value ff ff ff fe instead of 00 00 00 fe. A further subtlety is that the & is defined to operate only on int values1, so what happens is:
value is promoted to an int (ff ff ff fe).
0xff is an int literal (00 00 00 ff).
The & is applied to yield...
Test whether string is a valid integer
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[[ $var =~ ^-?[0-9]+$ ]]
The ^ indicates the beginning of the input pattern
The - is a literal "-"
The ? means "0 or 1 of the preceding (-)"
The + means "1 or more of the preceding ([0-9])"
The $ indicates the end of the input pattern
...