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Summarizing multiple columns with dplyr? [duplicate]
...u want to summarize only certain columns, use summarise_at or summarise_if functions.
Alternatively, the purrrlyr package provides the same functionality:
library(purrrlyr)
df %>% slice_rows("grp") %>% dmap(mean)
#> # A tibble: 3 x 5
#> grp a b c d
#> <int>...
Is it possible to define more than one function per file in MATLAB, and access them from outside tha
...hen I was studying for my undergraduate degree in EE, MATLAB required each function to be defined in its own file, even if it was a one-liner.
...
App Inventor 2 最新QA汇总 - App Inventor 2 中文网 - 清泛IT社区，有思想、有深度
...充进了文档，是官方的中文化升级版本。参考：https://www.fun123.cn/reference/info/ReleaseNotes.html
Q：ai2Starter模拟器中AI伴侣版本过旧，可否升级到最新版本？
A：有办法，但是过程较为复杂，需要一定的技术功底。而且这个模拟器...
分享几个App Inventor 2“隐藏”的非常的实用的小技巧 - App Inventor 2 中...
.../BV1Xj41147cn/
4、代码块导出图像，以及还原：https://www.fun123.cn/reference/other/download-pngs.html
5、iOS界面外观
6、过程参数，鼠标悬停时，可直接拖动获取和设置的代码块；参数可变：https://www.fun123.cn/reference/concepts/mutators.h...
Can a variable number of arguments be passed to a function?
...may find a time when they have to pass an unknown number of arguments to a function. In a case like this call your "manyArgs" by creating a list called "args" and passing that to manyArgs like this "manyArgs(*args)"
– wilbbe01
Feb 16 '11 at 6:02
...
How to match “any character” in regular expression?
...);
}
Now you can easily add new testcases and try new patterns. Have fun exploring regex.
See also
regular-expressions.info/Tutorial
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css让background-color在background-img的上边显示，且背景图片居中 - 更多...
... class="content" style="max-height:700px; background:green url(https: www fun123 cn css让background-color在background-img的上边显示，且背景图片居中的代码如下：
<div class="content" style="max-height:700px;
background:green url(https://www.fun123.cn/img/itso.png) no-repe...
App Inventor 2 中文网已全面升级https安全通道，数据安全有保障！ - App I...
经过一段时间的努力，App Inventor 2 中文网（fun123.cn）已全部升级https安全通道，以保护用户的访问及数据安全，值得注意的是MIT官方目前仍是http非安全通道。
App Inventor 2 中文网（fun123.cn）安全通道
MIT官方目前非安全通道...
轻松学习App开发？App Inventor 2 中文网搞定！ - App Inventor 2 中文网 -...
...么现在，我有一个好消息要告诉你，App Inventor 2 中文网（fun123 cn）能帮你搞定！App Inv
有没有想过自己动手开发一个属于自己的应用程序？有没有因为开发难度而望而却步？那么现在，我有一个好消息要告诉你，App Inventor 2 中...