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How to count TRUE values in a logical vector
...# gives you 1
length(z[z == TRUE]) # f3lix answer, gives you 2 (because NA indexing returns values)
So I think the safest is to use na.rm = TRUE:
sum(z, na.rm = TRUE) # best way to count TRUE values
(which gives 1). I think that table solution is less efficient (look at the code of table functi...
Cost of len() function
...
Calling len() on those data types is O(1) in CPython, the most common implementation of the Python language. Here's a link to a table that provides the algorithmic complexity of many different functions in CPython:
TimeComple...
HEAD and ORIG_HEAD in Git
...G_HEAD.
git reset --hard ORIG_HEAD
Resetting hard to it brings your index file and the working tree back to that state, and resets the tip of the branch to that commit.
git reset --merge ORIG_HEAD
After inspecting the result of the merge, you may find that the change in the other bran...
Razor-based view doesn't see referenced assemblies
...m another project in the same solution (with assembly name MyCoreDBLayer). All objects from MyCore.DBLayer worked perfectly in Controllers and Models but failed in Razor views with an error 'The type or namespace name 'DBLayer' does not exist in the namespace 'MyCore' (are you missing an assembly re...
mongodb count num of distinct values per field/key
...}
},
{ $unwind: "$keywords" },
{
$group: {
_id: {$toLower: '$keywords'},
count: { $sum: 1 }
}
},
{
$match: {
count: { $gte: 2 }
}
},
{ $sort : { count : -1} },
{ $limit : 100 }
]);
that give result ...
手机测高仪 · App Inventor 2 中文网
...ch, roll) {
if not (已锁定) {
当前仰角 = abs(pitch)
标签_角度.Text = join("当前仰角：", round(当前仰角), "°")
}
}
方向改变时 这个事件，只要手机一动就会触发，数字会实时跳。
这里用了 abs() 取绝对值，原因是：不同手机、不...
What is array to pointer decay?
...r to int. That pointer can be compared with the variable ip.
In the array indexing syntax you are used to seeing, again, the arr is 'decayed to a pointer'
arr[42];
/* same as *(arr + 42); */
/* same as *(&(arr[0]) + 42); */
The only times an array doesn't decay into a pointer are when it is ...
What is the Swift equivalent to Objective-C's “@synchronized”?
...ty that you have with @synchronized.
– Michael Waterfall
Oct 23 '14 at 16:46
9
With this approach...
How to convert Java String into byte[]?
...m you appear to be wrestling with is that this doesn't display very well. Calling toString() will just give you the default Object.toString() which is the class name + memory address. In your result [B@38ee9f13, the [B means byte[] and 38ee9f13 is the memory address, separated by an @.
For display ...
Read entire file in Scala?
...simple and canonical way to read an entire file into memory in Scala? (Ideally, with control over character encoding.)
18 ...