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MongoDB Aggregation: How to get total records count?
...sults are stored as an array of documents.
In this particular case, this means that one can do something like this:
$result = $collection->aggregate([
{ ...execute queries, group, sort... },
{ ...execute queries, group, sort... },
{ ...execute queries, group, sort... },
$facet: {
p...
What does the 'L' in front a string mean in C++?
...
'L' means wchar_t, which, as opposed to a normal character, requires 16-bits of storage rather than 8-bits. Here's an example:
"A" = 41
"ABC" = 41 42 43
L"A" = 00 41
L"ABC" = 00 41 00 42 00 43
A wchar_t is twice big as a...
How to remove old Docker containers
...
What do you mean "storage containers"? If you mean data-only containers which once upon a time were used to keep references to data volumes, those are no longer necessary because of the availability of docker volume subcommand, and named...
How to get form field's id in Django?
...
I think what you mean is that you can use "auto_id" for the id, but you have to use "html_name" for the name. Sadly I find your answer is worded confusingly given the question.
– Steve
Nov 1 '12 at 21:04...
What is the Git equivalent for revision number?
... with "fatal: No names found, cannot describe anything." - Stack Overflow; meaning that you'd have to set up tags yourself.
– sdaau
Apr 21 '13 at 19:41
14
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What's the difference between lapply and do.call?
...example with a list :
X <- list(1:3,4:6,7:9)
With lapply you get the mean of every element in the list like this :
> lapply(X,mean)
[[1]]
[1] 2
[[2]]
[1] 5
[[3]]
[1] 8
do.call gives an error, as mean expects the argument "trim" to be 1.
On the other hand, rbind binds all arguments ro...
Can I use non existing CSS classes?
...ts, and your markup is perfectly valid as it is.
This doesn't necessarily mean that you need to have a class declared in the HTML before you can use it in CSS either. See ruakh's comment. Whether or not a selector is valid depends entirely on the selector syntax, and CSS has its own set of rules fo...
How do I map lists of nested objects with Dapper
...ation to course? It'sessentially the same thing minus the inner join which means sql wont transfer as many bytes?
– MIKE
May 31 '18 at 17:10
...
Assign multiple columns using := in data.table, by group
...hello
# 4: 1 4 hi hello
# 5: 2 5 hi hello
# 6: 3 6 hi hello
x[ , c("mean", "sum") := list(mean(b), sum(b)), by = a][]
# a b col1 col2 mean sum
# 1: 1 1 hi hello 2.5 5
# 2: 2 2 hi hello 3.5 7
# 3: 3 3 hi hello 4.5 9
# 4: 1 4 hi hello 2.5 5
# 5: 2 5 hi hello 3.5 7
#...
What do REFRESH and MERGE mean in terms of databases?
...
REFRESH means "pull any state changes from the database into my representation". Cascading this is simple; it means that all associated entities are refreshed.
MERGE means something complex that approximates "save" but is more like...