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How to force R to use a specified factor level as reference in a regression?
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See the relevel() function. Here is an example:
set.seed(123)
x <- rnorm(100)
DF <- data.frame(x = x,
y = 4 + (1.5*x) + rnorm(100, sd = 2),
b = gl(5, 20))
head(DF)
str(DF)
m1 <- lm(y ~ x + b, data = DF)
summary(m1)
Now alter the factor b...
Difference between Big-O and Little-O Notation
...rue if you used little-o:
x² ∈ O(x²)
x² ∈ O(x² + x)
x² ∈ O(200 * x²)
The following are true for little-o:
x² ∈ o(x³)
x² ∈ o(x!)
ln(x) ∈ o(x)
Note that if f ∈ o(g), this implies f ∈ O(g). e.g. x² ∈ o(x³) so it is also true that x² ∈ O(x³), (again, think of ...
Random hash in Python
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A md5-hash is just a 128-bit value, so if you want a random one:
import random
hash = random.getrandbits(128)
print("hash value: %032x" % hash)
I don't really see the point, though. Maybe you should elaborate why you need this...
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Java: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification
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22 Answers
22
Active
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JPA: How to have one-to-many relation of the same Entity type
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2 Answers
2
Active
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How to execute IN() SQL queries with Spring's JDBCTemplate effectivly?
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276
You want a parameter source:
Set<Integer> ids = ...;
MapSqlParameterSource parameters ...
How to compile a static library in Linux?
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211
See Creating a shared and static library with the gnu compiler [gcc]
gcc -c -o out.o out.c
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Regex to remove all (non numeric OR period)
...s and periods should stay - everything else filtered. I use C# and VS.net 2008 framework 3.5
5 Answers
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Get last dirname/filename in a file path argument in Bash
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answered Jul 20 '10 at 20:29
sthsth
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Difference between java.util.Random and java.security.SecureRandom
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236
The standard Oracle JDK 7 implementation uses what's called a Linear Congruential Generator t...