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What is “callback hell” and how and why does RX solve it?
...e from event handling code. You can easily handle details like async event ordering that are a nightmare when using state variables. I found RX was the cleanest implementation to perform a new network request after 3 network responses returned or to error handle the whole chain if one does not retur...
Find rows that have the same value on a column in MySQL
...LECT email,
count(*) AS c
FROM TABLE
GROUP BY email
HAVING c > 1
ORDER BY c DESC
If you want the full rows:
select * from table where email in (
select email from table
group by email having count(*) > 1
)
...
Google App Engine: Is it possible to do a Gql LIKE query?
...%")
You can do something like a startWith, or endWith if you reverse the order when stored and searched. You do a range query with the starting value you want, and a value just above the one you want.
String start = "foo";
... = ofy.query(MyEntity.class).filter("field >=", start).filter("...
Is it better practice to use String.format over string Concatenation in Java?
...thout requiring a recompile of the executable to account for the different ordering. With argument positions you can also re-use the same argument without passing it into the function twice:
String.format("Hello %1$s, your name is %1$s and the time is %2$t", name, time)
...
Check if multiple strings exist in another string
... if x in str]
If you want to get all non-duplicate matches (disregarding order):
matches = {x for x in a if x in str}
If you want to get all non-duplicate matches in the right order:
matches = []
for x in a:
if x in str and x not in matches:
matches.append(x)
...
Replacement for “rename” in dplyr
...onious solution but this works and preserves all columns (though not their order). disp does not get duplicated.
– farnsy
Aug 22 '14 at 3:38
...
Python: Check if one dictionary is a subset of another larger dictionary
...;= d2.items() are actually comparing 2 lists of tuples, without particular order, so the final result will probably not reliable. For this reason, I switch to @blubberdiblub 's answer.
– RayLuo
Feb 17 '17 at 20:43
...
Should I make HTML Anchors with 'name' or 'id'?
...hat has an ID exactly equal to fragid, then the first such element in tree order is the indicated part of the document; stop the algorithm here.
If there is an a element in the DOM that has a name attribute whose value is exactly equal to fragid, then the first such element in tree order is the...
SparseArray vs HashMap
...;
sparseArray.put(17, "pig");
Note that the int keys do not need to be in order. This can also be used to change the value at a particular int key.
Remove items
Use remove (or delete) to remove elements from the array.
sparseArray.remove(17); // "pig" removed
The int parameter is the integer key.
...
Replacing NAs with latest non-NA value
... = TRUE), y = sample(c(1:4, rep(NA, 4)), 20 , replace = TRUE))
dt <- dt[order(group)]
dt[, y_forward_fill := y[1], .(group, cumsum(!is.na(y)))]
dt
group y y_forward_fill
1: a NA NA
2: a NA NA
3: a NA NA
4: a 2 2
5: a ...