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What are the underlying data structures used for Redis?
...ave all kinds of Top Something lists in your web application. Top users by score, top posts by pageviews, top whatever, but a single Redis instance will support tons of insertion and get-top-elements operations per second.
Sorted sets, like regular sets, can be used to describe relations, but they ...
Compare two DataFrames and output their differences side-by-side
...changed.index.names = ['id', 'col']
In [26]: changed
Out[26]:
id col
1 score True
2 isEnrolled True
Comment True
dtype: bool
Here the first entry is the index and the second the columns which has been changed.
In [27]: difference_locations = np.where(df1 != df2)
In [28...
How do I sort an NSMutableArray with custom objects in it?
...s of my array from id to my class type.
In this case it was a class called Score with a property called points.
Also you need to decide what to do if the elements of your array are not the right type, for this example I just returned NSOrderedSame, however in my code I though an exception.
NSArray...
Why do I get “Pickle - EOFError: Ran out of input” reading an empty file?
...
I would check that the file is not empty first:
import os
scores = {} # scores is an empty dict already
if os.path.getsize(target) > 0:
with open(target, "rb") as f:
unpickler = pickle.Unpickler(f)
# if file is not empty scores will be equal
# t...
How to get the top 10 values in postgresql?
...
For this you can use limit
select *
from scores
order by score desc
limit 10
If performance is important (when is it not ;-) look for an index on score.
Starting with version 8.4, you can also use the standard (SQL:2008) fetch first
select *
from scores
order ...
How can I convert a dictionary into a list of tuples?
... use namedtuple. For example, you have a dictionary of 'name' as keys and 'score' as values like:
d = {'John':5, 'Alex':10, 'Richard': 7}
You can list the items as tuples, sorted if you like, and get the name and score of, let's say the player with the highest score (index=0) very Pythonically li...
Delete rows from a pandas DataFrame based on a conditional expression involving len(string) giving K
...e boolean condition>].index)
Example
To remove all rows where column 'score' is < 50:
df = df.drop(df[df.score < 50].index)
In place version (as pointed out in comments)
df.drop(df[df.score < 50].index, inplace=True)
Multiple conditions
(see Boolean Indexing)
The operators are...
Sort a list by multiple attributes?
...on, that ranks a list of classes where each object is in a group and has a score function, but you can add any list of attributes.
Note the un-lambda-like, though hackish use of a lambda to call a setter.
The rank part won't work for an array of lists, but the sort will.
#First, here's a pure li...
What is the difference between int, Int16, Int32 and Int64?
...-- (-2,147,483,648 to +2,147,483,647)
Int64 -- (-9,223,372,036,854,775,808 to +9,223,372,036,854,775,807)
As stated by James Sutherland in his answer:
int and Int32 are indeed synonymous; int will be a little more
familiar looking, Int32 makes the 32-bitness more explicit to those
read...
How to sort List of objects by some property
...
Using Comparator
For Example:
class Score {
private String name;
private List<Integer> scores;
// +accessor methods
}
Collections.sort(scores, new Comparator<Score>() {
public int compare(Score o1, Score o2) {
...