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How to convert a boolean array to an int array
...t;>> x
array([ True, False, True], dtype=bool)
>>> x + [1, 2, 3]
array([2, 2, 4])
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What's the difference between “mod” and “remainder”?
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There is a difference between modulus and remainder. For example:
-21 mod 4 is 3 because -21 + 4 x 6 is 3.
But -21 divided by 4 gives -5 with a remainder of -1.
For positive values, there is no difference.
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Pandas dataframe get first row of each group
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248
>>> df.groupby('id').first()
value
id
1 first
2 first
3 first
4...
Why does Math.round(0.49999999999999994) return 1?
....1 This is a specification bug, for precisely this one pathological case.2 Java 7 no longer mandates this broken implementation.3
The problem
0.5+0.49999999999999994 is exactly 1 in double precision:
static void print(double d) {
System.out.printf("%016x\n", Double.doubleToLongBits(d));
}
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No provider for “framework:jasmine”! (Resolving: framework:jasmine)
....0",
"grunt-contrib-jshint": "~0.7.1",
"grunt-contrib-uglify": "~0.2.0",
"grunt-contrib-watch": "~0.5.2",
"grunt-google-cdn": "~0.2.0",
"grunt-newer": "~0.5.4",
"grunt-ngmin": "~0.0.2",
"grunt-rev": "~0.1.0",
"grunt-svgmin": "~0.2.0",
"grunt-usemin": "~2.0.0",
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Can dplyr package be used for conditional mutating?
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220
Use ifelse
df %>%
mutate(g = ifelse(a == 2 | a == 5 | a == 7 | (a == 1 & b == 4), 2,
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Reduce, fold or scan (Left/Right)?
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372
In general, all 6 fold functions apply a binary operator to each element of a collection. The re...
Unicode与UTF-8互转(C语言实现) - C/C++ - 清泛网 - 专注C/C++及内核技术
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位(bit)有0和1两种状态, 因此八个二进制位就可以组合出 256种状态, 这被称为一个字
节(byte). 也就是说, 一个字节一共可以用来表示256种不同的状态, 每一个状态对应一
个符号, 就是256个符号, 从 0000000到11111111.
上个世纪60年代...
dplyr summarise: Equivalent of “.drop=FALSE” to keep groups with zero length in output
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26
Since dplyr 0.8 group_by gained the .drop argument that does just what you asked for:
df = dat...
Find the max of two or more columns with pandas
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