829 questions
Score of 4708
38 answers
3271049 views
How slicing in Python works
How does Python's slice notation work? That is: when I write code like a[x:y:z], a[:], a[::2] etc., how can I understand which elements end up in the slice?
See Why are slice and range upper-bound ...
- reputation score 81381
Score of 30
11 answers
10203 views
Expand ranges defined by "from" and "to" columns
This problem is also known as 'transforming a "start-end" dataset to a panel dataset'
I have a data frame containing "name" of U.S. Presidents, the years when they start and end in ...
- reputation score 513
Score of 208
18 answers
783319 views
How do I reset a sequence in Oracle?
In PostgreSQL, I can do something like this:
ALTER SEQUENCE serial RESTART WITH 0;
Is there an Oracle equivalent?
- reputation score 17261
Score of 22
5 answers
6224 views
Create grouping variable for consecutive sequences and split vector
I have a vector, such as c(1, 3, 4, 5, 9, 10, 17, 29, 30) and I would like to group together the 'neighboring' elements that form a regular, consecutive sequence, i.e. an increase by 1, in a ragged ...
- reputation score 221
Score of 32
8 answers
22385 views
Convert Python sequence to NumPy array, filling missing values
The implicit conversion of a Python sequence of variable-length lists into a NumPy array cause the array to be of type object.
v = [[1], [1, 2]]
np.array(v)
>>> array([[1], [1, 2]], dtype=...
- reputation score 2163
Score of 42
1 answer
18026 views
PostgreSQL gapless sequences
I'm moving from MySql to Postgres, and I noticed that when you delete rows from MySql, the unique ids for those rows are re-used when you make new ones. With Postgres, if you create rows, and delete ...
- reputation score 2179
Score of 172
22 answers
192531 views
Hibernate JPA Sequence (non-Id)
Is it possible to use a DB sequence for some column that is not the identifier/is not part of a composite identifier?
I'm using hibernate as jpa provider, and I have a table that has some columns ...
- reputation score 18418
Score of 155
17 answers
126978 views
Sequence-zip function for C++11?
With the new range-based for-loop we can write code like:
for(auto x: Y) {}
Which IMO is a huge improvement from (for ex.)
for(std::vector<int>::iterator x=Y.begin(); x!=Y.end(); ++x) {}
Can ...
- reputation score 89048
Score of 162
7 answers
229861 views
Fixing the order of facets in ggplot
Data:
df <- data.frame(
type = c("T", "F", "P", "T", "F", "P", "T", "F", "P", "T", "F&...
- reputation score 2145
Score of 29
3 answers
32549 views
Create counter within consecutive runs of values
I wish to create a sequential number within each run of equal values, like a counter of occurrences, which restarts once the value in the current row is different from the previous row.
Please find ...
- reputation score 1316
Score of 73
7 answers
110795 views
Variables in bash seq replacement ({1..10}) [duplicate]
Is it possible to do something like this:
start=1
end=10
echo {$start..$end}
# Ouput: {1..10}
# Expected: 1 2 3 ... 10 (echo {1..10})
- reputation score 30450
Score of 108
3 answers
185867 views
Create sequence of repeated values, in sequence?
I need a sequence of repeated numbers, i.e. 1 1 ... 1 2 2 ... 2 3 3 ... 3 etc. The way I implemented this was:
nyear <- 20
names <- c(rep(1,nyear),rep(2,nyear),rep(3,nyear),rep(4,nyear),
...
- reputation score 1284
Score of 46
7 answers
251017 views
How do I create a sequence in MySQL?
I'm trying to create a sequence in MySQL (I'm very new to SQL as a whole). I'm using the following code, but it causes an error:
CREATE SEQUENCE ORDID INCREMENT BY 1 START WITH 622;
ORDID refers to a ...
- reputation score 1359
Score of 126
9 answers
600103 views
Create a group number for each consecutive sequence
I have the data.frame below. I want to add a column 'g' that classifies my data according to consecutive sequences in column h_no. That is, the first sequence of h_no 1, 2, 3, 4 is group 1, the second ...
- reputation score 1261
Score of 6
1 answer
18590 views
generate sequence within group in R [duplicate]
I am trying to obtain a sequence within category.
My data are:
A B
1 1
1 2
1 2
1 3
1 3
1 3
1 4
1 4
and I want to get variable "c" such as my data look like:
A B C
1 1 1
1 2 1
1 2 2
1 3 1
1 3 2
1 ...
- reputation score 293