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lenses, fclabels, data-accessor - which library for structure access and mutation is better
... a -> a)
providing two functions: a getter, and a setter
get (Lens g _) = g
put (Lens _ s) = s
subject to three laws:
First, that if you put something, you can get it back out
get l (put l b a) = b
Second that getting and then setting doesn't change the answer
put l (get l a) a = a
A...
How do PHP sessions work? (not “how are they used?”)
...on files are usually stored in, say, /tmp/ on the server, and named sess_{session_id} . I have been looking at the contents and cannot figure out how they really work.
...
How to convert a unix timestamp (seconds since epoch) to Ruby DateTime?
...cessary instead of DateTime. So use Time.strptime("1318996912345",'%Q').to_f and you will see the milliseconds preserved, while DateTime.strptime("1318996912345",'%Q').to_f does not preserve it.
– skensell
Feb 22 '17 at 15:20
...
Setting default value for TypeScript object passed as argument
...myParamsObject;
//Compiles to:
var firstName = myParamsObject.firstName,
_a = myParamsObject.lastName,
lastName = _a === void 0 ? 'Smith' : _a;
Writing an interface, type or class for the parameter object improves legibility.
type FullName = {
firstName: string;
/** @default 'S...
How does Dijkstra's Algorithm and A-Star compare?
...stance(int dist[], bool sptSet[])
{
// Initialize min value
int min = INT_MAX, min_index;
for (int v = 0; v < V; v++)
if (sptSet[v] == false && dist[v] <= min)
min = dist[v], min_index = v;
return min_index;
}
int printSolution(int dist[], int n)
{
printf("Vertex ...
get list from pandas dataframe column
...hon list. Alternatively you cast it with list(x).
import pandas as pd
data_dict = {'one': pd.Series([1, 2, 3], index=['a', 'b', 'c']),
'two': pd.Series([1, 2, 3, 4], index=['a', 'b', 'c', 'd'])}
df = pd.DataFrame(data_dict)
print(f"DataFrame:\n{df}\n")
print(f"column types:\n{df.dtyp...
Contains method for a slice
...st, but is trivial to write:
func contains(s []int, e int) bool {
for _, a := range s {
if a == e {
return true
}
}
return false
}
You can use a map if that lookup is an important part of your code, but maps have cost too.
...
Print PHP Call Stack
...
If you want to generate a backtrace, you are looking for debug_backtrace and/or debug_print_backtrace.
The first one will, for instance, get you an array like this one (quoting the manual) :
array(2) {
[0]=>
array(4) {
["file"] => string(10) "/tmp/a.php"
["line"] => ...
Convert tuple to list and back
...
List to Tuple and back can be done as below
import ast, sys
input_str = sys.stdin.read()
input_tuple = ast.literal_eval(input_str)
l = list(input_tuple)
l.append('Python')
#print(l)
tuple_2 = tuple(l)
# Make sure to name the final tuple 'tuple_2'
print(tuple_2)
...
What's the recommended approach to resetting migration history using Django South?
...r appname/migrations/
./manage.py reset south
./manage.py convert_to_south appname
(Notice that the “reset south” part clears migration records for ALL apps, so make sure you either run the other two lines for all apps or delete selectively).
The convert_to_south call at th...