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Postgresql aggregate array
...nt name on GROUP BY.
CREATE TABLE grade
(Student_id int, Mark varchar(2));
INSERT INTO grade
(Student_id, Mark)
VALUES
(1, 'A'),
(2, 'B'),
(2, 'B+'),
(3, 'C'),
(3, 'A');
CREATE TABLE student
(Id int primary key, Name varchar(5));
INSERT INTO student
(Id, Name...
How to find the key of the largest value hash?
I have the following hash {"CA"=>2, "MI"=>1, "NY"=>1}
7 Answers
7
...
Format number to 2 decimal places
I would like to know how can I output a number with 2 decimal places, without rounding the original number.
6 Answers
...
How to find the length of a string in R
...
424
See ?nchar. For example:
> nchar("foo")
[1] 3
> set.seed(10)
> strn <- paste(sampl...
Flatten an Array of Arrays in Swift
...
Swift >= 3.0
reduce:
let numbers = [[1,2,3],[4],[5,6,7,8,9]]
let reduced = numbers.reduce([], +)
flatMap:
let numbers = [[1,2,3],[4],[5,6,7,8,9]]
let flattened = numbers.flatMap { $0 }
joined:
let numbers = [[1,2,3],[4],[5,6,7,8,9]]
let joined = Array(number...
How do I write data into CSV format as string (not file)?
I want to cast data like [1,2,'a','He said "what do you mean?"'] to a CSV-formatted string.
6 Answers
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MySQL IF NOT NULL, then display 1, else display 0
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214
Instead of COALESCE(a.addressid,0) AS addressexists, use CASE:
CASE WHEN a.addressid IS NOT N...
Import pandas dataframe column as string not int
...
Just want to reiterate this will work in pandas >= 0.9.1:
In [2]: read_csv('sample.csv', dtype={'ID': object})
Out[2]:
ID
0 00013007854817840016671868
1 00013007854817840016749251
2 00013007854817840016754630
3 00013007854817840016781876
4 00013007854817...
How to sort Counter by value? - python
...
261
Use the Counter.most_common() method, it'll sort the items for you:
>>> from collect...
Regular expressions in C: examples?
...
238
Regular expressions actually aren't part of ANSI C. It sounds like you might be talking about ...