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When is “i += x” different from “i = i + x” in Python?
...he standard notation of i = i + . Is there a case in which i += 1 would be different from i = i + 1 ?
3 Answers
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Reference — What does this symbol mean in PHP?
This is a collection of questions that come up every now and then about syntax in PHP. This is also a Community Wiki, so everyone is invited to participate in maintaining this list.
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Why avoid increment (“++”) and decrement (“--”) operators in JavaScript?
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My view is to always use ++ and -- by themselves on a single line, as in:
i++;
array[i] = foo;
instead of
array[++i] = foo;
Anything beyond that can be confusing to some programmers and is just not worth it in my view. For loops are an exception, as the...
How to check if PHP array is associative or sequential?
PHP treats all arrays as associative, so there aren't any built in functions. Can anyone recommend a fairly efficient way to check if an array contains only numeric keys?
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How to swap keys and values in a hash
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Ruby has a helper method for Hash that lets you treat a Hash as if it was inverted (in essence, by letting you access keys through values):
{a: 1, b: 2, c: 3}.key(1)
=> :a
If you want to keep the inverted hash, then Hash#...
Split (explode) pandas dataframe string entry to separate rows
...ld and create a new row per entry (assume that CSV are clean and need only be split on ','). For example, a should become b :
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Is there XNOR (Logical biconditional) operator in C#?
I'm new to C# and could not find XNOR operator to provide this truth table:
4 Answers
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Compare two data.frames to find the rows in data.frame 1 that are not present in data.frame 2
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This doesn't answer your question directly, but it will give you the elements that are in common. This can be done with Paul Murrell's package compare:
library(compare)
a1 <- data.frame(a = 1:5, b = letters[1:5])
a2 <- data.frame(a = 1:3, b = letters[1:3])
compa...
Regex lookahead, lookbehind and atomic groups
I found these things in my regex body but I haven't got a clue what I can use them for.
Does somebody have examples so I can try to understand how they work?
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App Inventor 2 数学代码块 · App Inventor 2 中文网
... 最小值 (min)
最大值 (max)
平方根 (square root)
绝对值 (abs)
相反数 (neg)
对数 (log)
e^
四舍五入 (round)
上取整 (ceiling)
下取整 (floor)
求模 (modulo)
余数 (remainder)
商 (quotient)
正弦 (sin)
余弦 (cos)
正切 (tan)
反正弦 (asin...