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Build vs new in Rails 3
In the Rails 3 docs , the build method for associations is described as being the same as the new method, but with the automatic assignment of the foreign key. Straight from the docs:
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How to get a specific output iterating a hash in Ruby?
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328
hash.each do |key, array|
puts "#{key}-----"
puts array
end
Regarding order I should add...
Modulo operation with negative numbers
... sense, logically. Right?
Let's see what this leads to:
Example A. 5/(-3) is -1
=> (-1) * (-3) + 5%(-3) = 5
This can only happen if 5%(-3) is 2.
Example B. (-5)/3 is -1
=> (-1) * 3 + (-5)%3 = -5
This can only happen if (-5)%3 is -2
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NameError: global name 'unicode' is not defined - in Python 3
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Python 3 renamed the unicode type to str, the old str type has been replaced by bytes.
if isinstance(unicode_or_str, str):
text = unicode_or_str
decoded = False
else:
text = unicode_or_str.decode(encoding)
decoded =...
Modulo operator with negative values [duplicate]
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3 Answers
3
Active
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Reorder levels of a factor without changing order of values
...f <- data.frame(f = 1:4, g = letters[1:4])
df
# f g
# 1 1 a
# 2 2 b
# 3 3 c
# 4 4 d
levels(df$g)
# [1] "a" "b" "c" "d"
df$g <- factor(df$g, levels = letters[4:1])
# levels(df$g)
# [1] "d" "c" "b" "a"
df
# f g
# 1 1 a
# 2 2 b
# 3 3 c
# 4 4 d
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map function for objects (instead of arrays)
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38 Answers
38
Active
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How to do multiple arguments to map function where one remains the same in python?
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One option is a list comprehension:
[add(x, 2) for x in [1, 2, 3]]
More options:
a = [1, 2, 3]
import functools
map(functools.partial(add, y=2), a)
import itertools
map(add, a, itertools.repeat(2, len(a)))
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