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How do you query for “is not null” in Mongo?
...: 1 }
{ "_id" : ObjectId("544540f11b5cf91c4893eb99"), "otherField" : 2 }
Now, create the sparse index on imageUrl field:
db.foo.ensureIndex( { "imageUrl": 1 }, { sparse: true } )
{
"createdCollectionAutomatically" : false,
"numIndexesBefore" : 1,
"numIndexesAfter" : 2,
"ok" : 1
}
...
SVG gradient using CSS
...eferencing elements from other files. Not sure about IE9 (can't test right now, just give it a try).
– Thomas W
Dec 27 '12 at 11:07
54
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Difference between @import and link in CSS
...a 1000 page website and we link to a CSS file from every page on the site. Now let's imagine we want to add a second CSS file to all of those pages. We could edit all 1000 HTML files and add a second CSS link or a much better way would be to import the second CSS file from within the first file. We ...
Distributed sequence number generation?
...
OK, this is a very old question, which I'm first seeing now.
You'll need to differentiate between sequence numbers and unique IDs that are (optionally) loosely sortable by a specific criteria (typically generation time). True sequence numbers imply knowledge of what all other wor...
Why use softmax as opposed to standard normalization?
...set and thus the sum of the log-likelihood of each sample indexed by k:
Now, we only focus on the softmax here with z already given, so we can replace
with i being the correct class of the kth sample. Now, we see that when we take the logarithm of the softmax, to calculate the sample's log-lik...
How to replace a character with a newline in Emacs?
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It's really a good idea for the characters which I don't know the key bind.
– Lei
Mar 5 '09 at 18:16
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How do I enumerate through a JObject?
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Now how do I use it for nested JSON? For example, if the "value" contains another set of key:value pairs, how can I use the JToken value to iterate through next set of pairs?
– AlbatrossCafe
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insert vs emplace vs operator[] in c++ map
...ou be able to use this call? v.emplace(v.end(), 10, 10); ...or would you now need to use: v.emplace(v.end(), foo(10, 10) ); ?
– Kaitain
Dec 18 '15 at 15:50
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How to optimize for-comprehensions and loops in Scala?
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Now, in 2014, I tested this again and for me performance is the following: java -> 0.3s; scala -> 3.6s; scala optimized -> 3.5s; scala functional -> 4s; Looks much better than 3 years ago, but... Still th...
What does auto&& tell us?
...fact that it was originally either an lvalue or an rvalue, your code says: Now that I've got your object from either an lvalue or rvalue expression, I want to preserve whichever valueness it originally had so I can use it most efficiently - this might invalidate it. As in:
auto&& var = some...