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通信连接组件 · App Inventor 2 中文网
...解码传输
KIO4_Base64 拓展：更强大的图像Base64编解码工具，解码后的图像可写入到文件
MQTT 拓展：轻量级物联网传输协议
Socket 拓展：TCP/IP传输协议
Activity启动器
使用启动Activity方法启动一个Activity（活动）的组...
Objective-C 2.0 Mac和iOS开发实践指南 PDF扫描版 - 文档下载 - 清泛网 - ...
...C的基础
1.1. C程序的结构
1.1.1. main函数
1.1.2 格式化
1.1.3 注释
1.1.4 变量和函数名
1.1.5 命名惯例
1.1.6 文件
1.2 变量
1.2.1. 整数类型
1.2.2 浮点类型
1.2.3 真值
1.2.4 初始化
1.2.5 指针
1.2.6 数组
1.2.7 字符串
1.2.8 结构
1.2.9 typede...
How do I make a matrix from a list of vectors in R?
...ne option is to use do.call():
> do.call(rbind, a)
[,1] [,2] [,3] [,4] [,5] [,6]
[1,] 1 1 2 3 4 5
[2,] 2 1 2 3 4 5
[3,] 3 1 2 3 4 5
[4,] 4 1 2 3 4 5
[5,] 5 1 2 3 4 5
[6,] 6 1 2 3 ...
Summarizing multiple columns with dplyr? [duplicate]
...df %>% group_by(grp) %>% summarise_all(list(mean))
#> # A tibble: 3 x 5
#> grp a b c d
#> <int> <dbl> <dbl> <dbl> <dbl>
#> 1 1 3.08 2.98 2.98 2.91
#> 2 2 3.03 3.04 2.97 2.87
#> 3 3 2.85 2.95 2.95 3.06...
Calculate difference in keys contained in two Python dictionaries
...
234
You can use set operations on the keys:
diff = set(dictb.keys()) - set(dicta.keys())
Here is...
Determine the data types of a data frame's columns
...o use ?str(). To explore some examples, let's make some data:
set.seed(3221) # this makes the example exactly reproducible
my.data <- data.frame(y=rnorm(5),
x1=c(1:5),
x2=c(TRUE, TRUE, FALSE, FALSE, FALSE),
X3=letters[1:5])
...
PHP Pass by reference in foreach [duplicate]
...ee');
foreach ($a as &$v) {
}
foreach ($a as $v) {
echo $v.'-'.$a[3].PHP_EOL;
}
As you can see, the last array item takes the current loop value: 'zero', 'one', 'two', and then it's just 'two'... : )
share
...
Regular expression that matches valid IPv6 addresses
...
30 Answers
30
Active
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Converting int to bytes in Python 3
I was trying to build this bytes object in Python 3:
13 Answers
13
...
“Cloning” row or column vectors
...
83
Here's an elegant, Pythonic way to do it:
>>> array([[1,2,3],]*3)
array([[1, 2, 3],
...