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How to reorder data.table columns (without copying)
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2 Answers
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How to format time since xxx e.g. “4 minutes ago” similar to Stack Exchange sites
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25 Answers
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Is there an R function for finding the index of an element in a vector?
...rks on vectors :
x <- sample(1:10)
x
# [1] 4 5 9 3 8 1 6 10 7 2
match(c(4,8),x)
# [1] 1 5
match only returns the first encounter of a match, as you requested. It returns the position in the second argument of the values in the first argument.
For multiple matching, %in% is the way to...
Get distance between two points in canvas
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211
You can do it with pythagoras theorem
If you have two points (x1, y1) and (x2, y2)
then you c...
Installing Numpy on 64bit Windows 7 with Python 2.7.3 [closed]
...nstaller for Numpy is for Numpy version 1.3.0 which only works with Python 2.6
6 Answers
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Why does ~True result in -2?
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240
int(True) is 1.
1 is:
00000001
and ~1 is:
11111110
Which is -2 in Two's complement1
1 ...
How do I list all versions of a gem available at a remote site?
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205
Well, it was easier than I thought (well, not really, let's say as easy as it should be):
gem...
warning: [options] bootstrap class path not set in conjunction with -source 1.5
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102
From a blog post:
To use javac from JDK N to cross-compiler to an older platform version, th...
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...
python numpy machine epsilon
...for a given float type is to use np.finfo():
print(np.finfo(float).eps)
# 2.22044604925e-16
print(np.finfo(np.float32).eps)
# 1.19209e-07
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