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App Inventor 2 如何下载/保存网络图片？ - App Inventor 2 中文网 - 清泛...
App Inventor 2 如何下载/保存网络图片？ai2_down_webpics首先，需要使用Web客户端组件，需要和网络url进行数据交互的场景就要考虑使用它，Web客户端组件在通信连接抽屉中：设置好网络图片的url，然后执行Get方法即可，代码如下：其...
App Inventor 2 复制屏幕功能，误删组件的“后悔药”，界面设计更便捷 - Ap...
App Inventor 2 复制屏幕功能，误删组件的“后悔药”，界面设计更便捷复制屏幕功能全新上线，中文网独有（MIT没有此功能），可以复制屏幕中的普通组件、图片、附件、拓展、代码块。更多升级详情可查看发布日志。下面演示一...
App Inventor 2 如何比较两个日期/时间？ - App Inventor 2 中文网 - 清泛...
App Inventor 2 如何比较两个日期/时间？利用计时器组件的相关方法：比较两个日期/时间对象的毫秒数，具体请参见文档：https://www.fun123.cn/reference/ ... tml#Clock.GetMillis即时时间的获取方法：1、日期/时间选择...利用计时器组件的相关...
Easy way to list node modules I have npm linked?
...symlinks, you could try something like find / -type d -name "node_modules" 2>/dev/null | xargs -I{} find {} -type l -maxdepth 1 | xargs ls -l.
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How to check if element in groovy array/hash/collection/list?
...n array contains an element?
I thought there might be something like [1, 2, 3].includes(1) which would evaluate as true .
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How to reverse a singly linked list using only two pointers?
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Sort a list by multiple attributes?
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A key can be a function that returns a tuple:
s = sorted(s, key = lambda x: (x[1], x[2]))
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Why does the indexing start with zero in 'C'?
...be denoted as array[0].
For more info:
http://developeronline.blogspot.com/2008/04/why-array-index-should-start-from-0.html
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How can I get a list of locally installed Python modules?
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Solutio...
Pass a data.frame column name to a function
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You can just use the column name directly:
df <- data.frame(A=1:10, B=2:11, C=3:12)
fun1 <- function(x, column){
max(x[,column])
}
fun1(df, "B")
fun1(df, c("B","A"))
There's no need to use substitute, eval, etc.
You can even pass the desired function as a parameter:
fun1 <- function...