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How to test multiple variables against a value?
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You misunderstand how boolean expressions work; they don't work like an English sentence and guess that you are talking about the same comparison for all names here. You are looking for:
if x == 1 or y == 1 or z == 1:
x and y are otherwise evaluated on ...
How can you do anything useful without mutable state?
...ples and say "Here, don't you see" -- but if you don't understand the syntax and underlying principles, then your eyes just glaze over. From your point of view, it looks as if I'm doing the same thing as an imperative language, but just setting up all kinds of boundaries to purposefully make program...
MD5 algorithm in Objective-C
.../ This is the md5 call
return [NSString stringWithFormat:
@"%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x",
result[0], result[1], result[2], result[3],
result[4], result[5], result[6], result[7],
result[8], result[9], result[10], result[11],
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How can I view the source code for a function?
...risked
"Non-visible functions are asterisked" means the function is not exported from its package's namespace. You can still view its source code via the ::: function (i.e. stats:::t.ts), or by using getAnywhere(). getAnywhere() is useful because you don't have to know which package the function...
How do you calculate the average of a set of circular data? [closed]
I want to calculate the average of a set of circular data. For example, I might have several samples from the reading of a compass. The problem of course is how to deal with the wraparound. The same algorithm might be useful for a clockface.
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How to split/partition a dataset into training and test datasets for, e.g., cross validation?
...ndom.permutation if you need to keep track of the indices:
import numpy
# x is your dataset
x = numpy.random.rand(100, 5)
numpy.random.shuffle(x)
training, test = x[:80,:], x[80:,:]
or
import numpy
# x is your dataset
x = numpy.random.rand(100, 5)
indices = numpy.random.permutation(x.shape[0])
t...
Remove all values within one list from another list? [duplicate]
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>>> a = range(1, 10)
>>> [x for x in a if x not in [2, 3, 7]]
[1, 4, 5, 6, 8, 9]
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Custom HTTP headers : naming conventions
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The recommendation is was to start their name with "X-". E.g. X-Forwarded-For, X-Requested-With. This is also mentioned in a.o. section 5 of RFC 2047.
Update 1: On June 2011, the first IETF draft was posted to deprecate the recommendation of using the "X-" prefix for non-st...
Regex exactly n OR m times
Consider the following regular expression, where X is any regex.
6 Answers
6
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Getting and removing the first character of a string
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See ?substring.
x <- 'hello stackoverflow'
substring(x, 1, 1)
## [1] "h"
substring(x, 2)
## [1] "ello stackoverflow"
The idea of having a pop method that both returns a value and has a side effect of updating the data stored in x is v...