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What's the difference between ES6 Map and WeakMap?
...er will notice that this API could
be implemented in JavaScript with two arrays (one for keys, one for
values) shared by the 4 API methods. Such an implementation would have
two main inconveniences. The first one is an O(n) search (n being the
number of keys in the map). The second one is a ...
mongodb find by multiple array items
... This helped me too, I needed it to find an object ID in an array, and where something like $in: [ ObjectId("4f9f2c336b810d0cf0000017") ] failed, $in: [ "4f9f2c336b810d0cf0000017" ] worked
– jbnunn
May 3 '12 at 15:43
...
Java: function for arrays like PHP's join()?
...ons Lang has a StringUtils class which has a join function which will join arrays together to make a String.
For example:
StringUtils.join(new String[] {"Hello", "World", "!"}, ", ")
Generates the following String:
Hello, World, !
...
Generate random string/characters in JavaScript
...(n^2) behavior. If you want to create longer strings, you should create an array of individual characters and join them together at the end.
– dan_waterworth
May 10 '12 at 10:55
10...
Algorithm to generate all possible permutations of a list?
...
Here is an algorithm in Python that works by in place on an array:
def permute(xs, low=0):
if low + 1 >= len(xs):
yield xs
else:
for p in permute(xs, low + 1):
yield p
for i in range(low + 1, len(xs)):
xs[low]...
NumPy or Pandas: Keeping array type as integer while having a NaN value
Is there a preferred way to keep the data type of a numpy array fixed as int (or int64 or whatever), while still having an element inside listed as numpy.NaN ?
...
python pandas remove duplicate columns
...me are ['alpha','beta','alpha']
df.columns.duplicated() returns a boolean array: a True or False for each column. If it is False then the column name is unique up to that point, if it is True then the column name is duplicated earlier. For example, using the given example, the returned value would ...
What do people find difficult about C pointers? [closed]
...ary developers use pointers-to-pointers-to-pointers, and if they expect an array of those things, well why not just pass a pointer to that too.
void foo(****ipppArr);
to call this, I need the address of the array of pointers to pointers to pointers of ints:
foo(&(***ipppArr));
In six month...
python list by value not by reference [duplicate]
...
For 2D arrays it's possible use map function: old_array = [[2, 3], [4, 5]] # python2.* new_array = map(list, old_array) # python3.* new_array = list(map(list, old_array))
– Pythoner
Jun 25 '18...
Mimicking sets in JavaScript?
...includes strings, numbers, dates, etc...
// It does not include objects or arrays though
// one could implement a toString() operator
// on an object that would uniquely identify
// the object.
//
// Uses a javascript object to hold the Set
//
// This is a subset of the Set object designed...