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Dynamically select data frame columns using $ and a character value
... 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. Sec...
How do I make a list of data frames?
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135
This isn't related to your question, but you want to use = and not <- within the function ca...
LINGO使用指南 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...如下的LP问题：
在模型窗口中输入如下代码：
min=2*x1+3*x2;
x1+x2>=350;
x1>=100;
2*x1+x2<=600;
然后点击工具条上的按钮 即可。
例1.2 使用LINGO软件计算6个发点8个收点的最小费用运输问题。产销单位运价如下表。
销地
...
How to get device make and model on iOS?
...", BUT I was wondering if it's possible to detect/know if I have an iPhone 3GS vs. and iPhone 4 vs. an iPhone 4S (in actuality, all I really want to do is determine if I have a 3G or not, because I'm doing fairly graphics intensive stuff) .
...
Multiple linear regression in Python
... my dependent variable (y) against several independent variables (x1, x2, x3, etc.).
13 Answers
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How to produce a range with step n in bash? (generate a sequence of numbers with increments)
...n its own).
Note that seq allows floating-point numbers (e.g., seq .5 .25 3.5) but bash's brace expansion only allows integers.
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How to drop columns by name in a data frame
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389
You should use either indexing or the subset function. For example :
R> df <- data.fram...
In OS X Lion, LANG is not set to UTF-8, how to fix it?
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312
I noticed the exact same issue when logging onto servers running Red Hat from an OSX Lion mach...
How to work around the stricter Java 8 Javadoc when using Maven
...Just add that to your POM and you're good to go.
For maven-javadoc-plugin 3.0.0 users:
Replace
<additionalparam>-Xdoclint:none</additionalparam>
by
<doclint>none</doclint>
Thanks @banterCZ!
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