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MongoDB: How to update multiple documents with a single command?
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For Mongo version > 2.2, add a field multi and set it to true
db.Collection.update({query},
{$set: {field1: "f1", field2: "f2"}},
{multi: true })
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How can I represent an infinite number in Python?
...= float("inf")
In Python 3.5, you can do:
import math
test = math.inf
And then:
test > 1
test > 10000
test > x
Will always be true. Unless of course, as pointed out, x is also infinity or "nan" ("not a number").
Additionally (Python 2.x ONLY), in a comparison to Ellipsis, float(inf...
Lint: How to ignore “ is not translated in ” errors?
I can't compile/debug our Android app, because the localization files are not perfect yet.
13 Answers
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In Java 8 how do I transform a Map to another Map using a lambda?
I've just started looking at Java 8 and to try out lambdas I thought I'd try to rewrite a very simple thing I wrote recently. I need to turn a Map of String to Column into another Map of String to Column where the Column in the new Map is a defensive copy of the Column in the first Map. Column has...
Is there any way to check if iOS app is in background?
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Thank you — and for additional clarity it's [[UIApplication sharedApplication] applicationState] == UIApplicationStateBackground.
– podperson
Jun 5 '12 at 16:01
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find() with nil when there are no records
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Yes, just do:
Challenge.find_by_id(10)
For Rails 4 and 5:
Challenge.find_by(id: 10)
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Extracting the last n characters from a string in R
...se R, but it's straight-forward to make a function to do this using substr and nchar:
x <- "some text in a string"
substrRight <- function(x, n){
substr(x, nchar(x)-n+1, nchar(x))
}
substrRight(x, 6)
[1] "string"
substrRight(x, 8)
[1] "a string"
This is vectorised, as @mdsumner point...
How do I extract a sub-hash from a hash?
...:d=>:D}
h1 = Hash[h1.to_a - h2.to_a] # => {:a=>:A, :c=>:C}
And if you want to patch that into the Hash class:
class Hash
def extract_subhash(*extract)
h2 = self.select{|key, value| extract.include?(key) }
self.delete_if {|key, value| extract.include?(key) }
h2
end
en...
Shortcuts in Objective-C to concatenate NSStrings
...factored). The function is also better implemented with an NSMutableString and -appendString to avoid creating an unbounded set of temporary autoreleased NSStrings.
– Rob Napier
Feb 16 '10 at 14:34
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super() raises “TypeError: must be type, not classobj” for new-style class
...e = OldStyle()
>>> issubclass(instance.__class__, object)
False
and not (as in the question):
>>> isinstance(instance, object)
True
For classes, the correct "is this a new-style class" test is:
>>> issubclass(OldStyle, object) # OldStyle is not a new-style class
Fal...