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For each row in an R dataframe
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Be careful, as the dataframe is converted to a matrix, and what you end up with (x) is a vector. This is why the above example has to use numeric indexes; the by() approach gives you a data.frame, which makes your code more robust.
– D...
Select all 'tr' except the first one
How can I select all tr elements except the first tr in a table with CSS?
10 Answers
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How can I select and upload multiple files with HTML and PHP, using HTTP POST?
... </body>
</html>
Here's what it looks like in Chrome after selecting 2 items in the file dialog:
And here's what it looks like after clicking the "Upload" button.
This is just a sketch of a fully working answer. See PHP Manual: Handling file uploads for more information on prop...
SQL Query Where Field DOES NOT Contain $x
...t is meant to be used in subqueries or with predefined lists:
-- subquery
SELECT a FROM x WHERE x.b NOT IN (SELECT b FROM y);
-- predefined list
SELECT a FROM x WHERE x.b NOT IN (1, 2, 3, 6);
If you are searching a string, go for the LIKE operator (but this will be slow):
-- Finds all rows where...
What is the fastest factorial function in JavaScript? [closed]
...000 will be truncated so if you're going to use this approach make sure to convert to exponential before using the aforementioned table.
– David Scott Kirby
May 2 '14 at 20:36
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How to avoid scientific notation for large numbers in JavaScript?
JavaScript converts a large INT to scientific notation when the number becomes large. How can I prevent this from happening?
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Is there a Python equivalent of the C# null-coalescing operator?
... so it works in a boolean context. If the values are not boolean, they are converted to boolean for the purposes of the operator.
Note that the or operator does not return only True or False. Instead, it returns the first operand if the first operand evaluates to true, and it returns the second ope...
How do I create an empty array/matrix in NumPy?
...might be best off to keep it in a list until it is finished, and only then convert it into an array.
e.g.
mylist = []
for item in data:
mylist.append(item)
mat = numpy.array(mylist)
item can be a list, an array or any iterable, as long
as each item has the same number of elements.
In this ...
How to test an SQL Update statement before running it?
...yway) you can also do a sanity check which rows are affected by running a select using the same WHERE clause as the UPDATE.
So if you UPDATE is
UPDATE foo
SET bar = 42
WHERE col1 = 1
AND col2 = 'foobar';
The following will show you which rows will be updated:
SELECT *
FROM foo
WHERE col1 ...
How to get size of mysql database?
...
Run this query and you'll probably get what you're looking for:
SELECT table_schema "DB Name",
ROUND(SUM(data_length + index_length) / 1024 / 1024, 1) "DB Size in MB"
FROM information_schema.tables
GROUP BY table_schema;
This query comes from the mysql forums, where there are...