大约有 6,886 项符合查询结果（耗时：0.0254秒） [XML]
Pandas every nth row
...use to get the nth data or drop the nth row is the following:
df1 = df[df.index % 3 != 0] # Excludes every 3rd row starting from 0
df2 = df[df.index % 3 == 0] # Selects every 3rd raw starting from 0
This arithmetic based sampling has the ability to enable even more complex row-selections.
This...
SQL keys, MUL vs PRI vs UNI
...
It means that the field is (part of) a non-unique index. You can issue
show create table <table>;
To see more information about the table structure.
share
|
improv...
How do HashTables deal with collisions?
...collision. I will explain some of them
Chaining:
In chaining we use array indexes to store the values. If hash code of second value also points to the same index then we replace that index value with an linked list and all values pointing to that index are stored in the linked list and actual array...
Right way to reverse pandas.DataFrame?
...
data.reindex(index=data.index[::-1])
or simply:
data.iloc[::-1]
will reverse your data frame, if you want to have a for loop which goes from down to up you may do:
for idx in reversed(data.index):
print(idx, data.loc[idx, ...
MongoDB: Is it possible to make a case-insensitive query?
...
Note that this will do a fullscan instead of using index.
– Martin Konicek
Apr 25 '13 at 13:29
13
...
Get the index of the nth occurrence of a string?
...s - you won't actually be checking any case twice, if you think about it. (IndexOf will return as soon as it finds the match, and you'll keep going from where it left off.)
share
|
improve this answ...
Nginx serves .php files as downloads, instead of executing them
...rking but... If I go to the main http://5.101.99.123 it's downloading my index.php :/
26 Answers
...
Why does PostgreSQL perform sequential scan on indexed column?
Very simple example - one table, one index, one query:
4 Answers
4
...
How to replace an item in an array with Javascript?
...
var index = items.indexOf(3452);
if (index !== -1) {
items[index] = 1010;
}
Also it is recommend you not use the constructor method to initialize your arrays. Instead, use the literal syntax:
var items = [523, 3452, 334, ...
How do I expand a tuple into variadic template function's arguments?
...o a variadic template function. Here is a small helper class which creates index array. It is used a lot in template metaprogramming:
// ------------- UTILITY---------------
template<int...> struct index_tuple{};
template<int I, typename IndexTuple, typename... Types>
struct make_ind...