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How to append rows to an R data frame
...sive insight than system.time:
library(microbenchmark)
microbenchmark(f1(1000), f3(1000), f4(1000), times = 5)
# Unit: milliseconds
# expr min lq median uq max neval
# f1(1000) 1024.539618 1029.693877 1045.972666 1055.25931 1112.769176 5
# f3(1000) ...
How do I count the number of occurrences of a char in a String?
...
answered Nov 29 '09 at 22:23
CowanCowan
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How to create NS_OPTIONS-style bitmask enumerations in Swift?
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Swift 3.0
Almost identical to Swift 2.0. OptionSetType was renamed to OptionSet and enums are written lower case by convention.
struct MyOptions : OptionSet {
let rawValue: Int
static let firstOption = MyOptions(rawValue:...
Convert NaN to 0 in javascript
Is there a way to convert NaN values to 0 without an if statement:
11 Answers
11
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Divide a number by 3 without using *, /, +, -, % operators
... x = t;
}
return y;
}
int divideby3(int num)
{
int sum = 0;
while (num > 3) {
sum = add(num >> 2, sum);
num = add(num >> 2, num & 3);
}
if (num == 3)
sum = add(sum, 1);
return sum;
}
As Jim commented this works, because:...
What is the maximum length of latitude and longitude? [closed]
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If latitude coordinate is reported as -6.3572375290155 or -63.572375290155 in decimal degrees then you could round-off and store up to 6 decimal places for 10 cm (or 0.1 meter) precision.
Overview
The valid range of latitude in degrees is -90 and +90 for the southern and nor...
Format number to 2 decimal places
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You want to use the TRUNCATE command.
https://dev.mysql.com/doc/refman/8.0/en/mathematical-functions.html#function_truncate
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...达式元字符
8. POSIX字符集
9. 匹配操作符(~)
10. 比较表达式
11. 范围模板
12. 一个验证passwd文件有效性的例子
13. 几个实例
14. awk编程
14.1. 变量
14.2. BEGIN模块
14.3. END模块
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Cluster analysis in R: determine the optimal number of clusters
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1024
If your question is how can I determine how many clusters are appropriate for a kmeans analysi...
Random float number generation
...need to employ a more advanced method.
This will generate a number from 0.0 to 1.0, inclusive.
float r = static_cast <float> (rand()) / static_cast <float> (RAND_MAX);
This will generate a number from 0.0 to some arbitrary float, X:
float r2 = static_cast <float> (rand()) / ...