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Pandas get topmost n records within each group
...
EDIT: As mentioned by the questioner, use df.groupby('id').head(2).reset_index(drop=True) to remove the multindex and flatten the results.
>>> df.groupby('id').head(2).reset_index(drop=True)
id value
0 1 1
1 1 2
2 2 1
3 2 2
4 3 1
5 4 1
...
Hash Map in Python
... self.store = [None for _ in range(16)]
def get(self, key):
index = hash(key) & 15
if self.store[index] is None:
return None
n = self.store[index]
while True:
if n.key == key:
return n.value
else:
...
Custom Cell Row Height setting in storyboard is not responding
... this method:
- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath;
In the function of a row you can choose Height. For example,
- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
if (indexPath.row == 0) ...
How to avoid passing parameters everywhere in play2?
...
Then in your actions you’ll be able to just write the following:
def index = Action {
Ok(views.html.index())
}
def index2 = Action {
Ok(views.html.index2())
}
You can find more information about this approach in this blog post and in this code sample.
Update: A nice blog post demonstra...
Quick easy way to migrate SQLite3 to MySQL? [closed]
...nes starting with:
BEGIN TRANSACTION
COMMIT
sqlite_sequence
CREATE UNIQUE INDEX
are not used in MySQL
SQLite uses CREATE TABLE/INSERT INTO "table_name" and MySQL uses CREATE TABLE/INSERT INTO table_name
MySQL doesn't use quotes inside the schema definition
MySQL uses single quotes for strings ins...
How to create a sub array from another array in Java?
...to create a sub-array from another array? Is there a method that takes the indexes from the first array such as:
9 Answers
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Storing sex (gender) in database
... a need to port.
Conclusion
I would use Option 2: CHAR(1).
Addendum
An index on the gender column likely would not help because there's no value in an index on a low cardinality column. Meaning, there's not enough variety in the values for the index to provide any value.
...
How to COUNT rows within EntityFramework without loading contents?
...ce SQL Server really can't do anything but do a full table scan (clustered index scan).
Sometimes, it's good enough to know an approximate number of rows from the database, and in such a case, a statement like this might suffice:
SELECT
SUM(used_page_count) * 8 AS SizeKB,
SUM(row_count) ...
Best way to test if a row exists in a MySQL table
...on in the comments, that in this situation:
SELECT 1 FROM my_table WHERE *indexed_condition* LIMIT 1
Is superior to:
SELECT * FROM my_table WHERE *indexed_condition* LIMIT 1
This is because the first query can be satisfied by the index, whereas the second requires a row look up (unless possibl...
MySQL case insensitive select
...e, comparisons are case-insensitive. You need to understand collations and indexes and configure those properly - using string transformations like LOWER() or an arbitrary COLLATE clause can completely bypass an index, and over time, as your table grows, this can have drastic performance implication...