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For each row return the column name of the largest value
...d() to make examples using sample reproducible):
DF <- data.frame(V1=c(2,8,1),V2=c(7,3,5),V3=c(9,6,4))
colnames(DF)[apply(DF,1,which.max)]
[1] "V3" "V1" "V2"
A faster solution than using apply might be max.col:
colnames(DF)[max.col(DF,ties.method="first")]
#[1] "V3" "V1" "V2"
...where ties...
How to drop columns by name in a data frame
... or the subset function. For example :
R> df <- data.frame(x=1:5, y=2:6, z=3:7, u=4:8)
R> df
x y z u
1 1 2 3 4
2 2 3 4 5
3 3 4 5 6
4 4 5 6 7
5 5 6 7 8
Then you can use the which function and the - operator in column indexation :
R> df[ , -which(names(df) %in% c("z","u"))]
x y
1 1...
Replacing NAs with latest non-NA value
...ample from the help page:
library(zoo)
az <- zoo(1:6)
bz <- zoo(c(2,NA,1,4,5,2))
na.locf(bz)
1 2 3 4 5 6
2 2 1 4 5 2
na.locf(bz, fromLast = TRUE)
1 2 3 4 5 6
2 1 1 4 5 2
cz <- zoo(c(NA,9,3,2,3,2))
na.locf(cz)
2 3 4 5 6
9 3 2 3 2
...
Comparing two dictionaries and checking how many (key, value) pairs are equal
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26 Answers
26
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How do I upgrade my ruby 1.9.2-p0 to the latest patch level using rvm?
My current version of ruby is ruby 1.9.2p0 (2010-08-18 revision 29036) [x86_64-darwin10.5.0] but I want to update it to the latest patch level using rvm. How can I do this?
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Why are these numbers not equal?
...entist Should Know About Floating-point Arithmetic," ACM Computing Surveys 23, 1 (1991-03), 5-48 doi>10.1145/103162.103163 (revision also available)
The Floating-Point Guide - What Every Programmer Should Know About Floating-Point Arithmetic
0.30000000000000004.com compares floating point arithme...
Insert an element at a specific index in a list and return the updated list
...can do b = a[:index] + [obj] + a[index:].
However, another way is:
a = [1, 2, 4]
b = a[:]
b.insert(2, 3)
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Find the most frequent number in a numpy vector
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12 Answers
12
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Python 3.x rounding behavior
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162
Python 3's way (called "round half to even" or "banker's rounding") is considered the standard r...
How to check the version before installing a package using apt-get?
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329
OK, I found it.
apt-cache policy <package name> will show the version details.
It also sh...