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Dynamically select data frame columns using $ and a character value
...is a reproducible example below:
# set seed for reproducibility
set.seed(123)
df <- data.frame( col1 = sample(5,10,repl=T) , col2 = sample(5,10,repl=T) , col3 = sample(5,10,repl=T) )
# We want to sort by 'col3' then by 'col1'
sort_list <- c("col3","col1")
# Use 'do.call' to call order. S...
How to have the cp command create any necessary folders for copying a file to a destination [duplica
... edited Nov 14 '12 at 19:05
Oz123
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answered Nov 14 '12 at 18:34
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Why are hexadecimal numbers prefixed with 0x?
...h is nicely divisible by 3 = log2(8).
The BCPL language used the syntax 8 1234 for octal numbers. When Ken Thompson created B from BCPL, he used the 0 prefix instead. This is great because
an integer constant now always consists of a single token,
the parser can still tell right away it's got a c...
How to “grep” for a filename instead of the contents of a file?
... giving you not only file names. but if a path has a directory ('/xyz_test_123/other.txt') would also comes to the result set.
cheers
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How can I refresh a page with jQuery?
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123
To reload a page with jQuery, do:
$.ajax({
url: "",
context: document.body,
succe...
Format date and time in a Windows batch script
...: 20140.01_131612 , must be(2014.10.26_131612)
– waza123
Oct 26 '14 at 11:16
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Detecting syllables in a word
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123
Read about the TeX approach to this problem for the purposes of hyphenation. Especially see Fr...
How to convert an NSString into an NSNumber
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For strings starting with integers, e.g., @"123", @"456 ft", @"7.89", etc., use -[NSString integerValue].
So, @([@"12.8 lbs" integerValue]) is like doing [NSNumber numberWithInteger:12].
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Store password in TortoiseHg
...the name of your GC project. So something like:
default = https://fred:xyz123@fredproj.googlecode.com/hg/
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组件使用指导 · App Inventor 2 中文网
...指导讲怎么用：工作原理、从零搭起来的完整案例和常见问题。
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图片轮播（ImageCarousel）：图片轮播：横向滑动切换多张图片，可自动播放、循环播放、显示圆点指示器
布局列表框（LayoutListView...