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How do you know when to use fold-left and when to use fold-right?
... you use a left fold. Example (haskell-style pseudocode)
foldl (-) [1, 2, 3] == (1 - 2) - 3 == 1 - 2 - 3 // - is left-associative
If your operator is right-associative (right fold), the parentheses would be set like this:
A x (B x (C x D))
Example: Cons-Operator
foldr (:) [] [1, 2, 3] == 1 : ...
JavaScript closure inside loops – simple practical example
...lock-scoping post as a great source of information.
for (let i = 0; i < 3; i++) {
funcs[i] = function() {
console.log("My value: " + i);
};
}
Beware, though, that IE9-IE11 and Edge prior to Edge 14 support let but get the above wrong (they don't create a new i each time, so all the funct...
How do I clone a range of array elements to a new array?
... create a new array containing all the elements from X that begin at index 3 and ends in index 7. Sure I can easily write a loop that will do it for me but I would like to keep my code as clean as possible. Is there a method in C# that can do it for me?
...
How to group dataframe rows into list in pandas groupby?
..., 'b':[1,2,5,5,4,6]})
df
Out[1]:
a b
0 A 1
1 A 2
2 B 5
3 B 5
4 B 4
5 C 6
In [2]: df.groupby('a')['b'].apply(list)
Out[2]:
a
A [1, 2]
B [5, 5, 4]
C [6]
Name: b, dtype: object
In [3]: df1 = df.groupby('a')['b'].apply(list).reset_index(name='new')
...
How do I get a list of all the duplicate items using pandas in python?
...
173
Method #1: print all rows where the ID is one of the IDs in duplicated:
>>> import pan...
jQuery .data() does not work, but .attr() does
...
213
I ran into a similar "bug" a few days ago when working with .data() and .attr('data-name') for H...
Bootstrap 3 - Why is row class is wider than its container?
I just started using Bootstrap 3. I am having a difficult time
understanding how the row class works.
Is there a way to avoid the padding-left and padding-right ?
...
Mysql order by specific ID values
...er by" using predefined set of column values (ID) like: order by (ID=1,5,4,3) so I would get record 1, 5, 4, 3 in that order out?
...
How to overcome TypeError: unhashable type: 'list'
...else:
d[key] = [value]
print d
# {'AAA': ['111', '112'], 'AAC': ['123'], 'AAB': ['111']}
Note that if you are using Python 3.x, you'll have to make a minor adjustment to get it work properly. If you open the file with rb, you'll need to use line = line.split(b'x') (which makes sure you are ...
Comparing strings with == which are declared final in Java
...
232
When you declare a String (which is immutable) variable as final, and initialize it with a comp...