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Array or List in Java. Which is faster?
...;std::string>, although copying by value without a pointer as such, the character arrays will form an object for string (and these will not usually be shared).
If this particular code is really performance-sensitive, you could create a single char[] array (or even byte[]) for all the characters ...
When to use reinterpret_cast?
... Nice example! I would replace short for uint16_t and unsigned char for uint8_t to make it less obscure for human.
– Jan Turoň
Aug 27 '18 at 9:41
1
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How to select the row with the maximum value in each group
In a dataset with multiple observations for each subject I want to take a subset with only the maximum data value for each record. For example, with a following dataset:
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Images can't contain alpha channels or transparencies
...rt to PNG without alpha in Preview. Simply open your image, choose export, select PNG, uncheck Alpha, and click Save. Preview also support batch export if you open all your images at once.
– Russell Ladd
Jan 7 '15 at 6:23
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With arrays, why is it the case that a[5] == 5[a]?
...D"[2] == *("ABCD" + 2) = *("CD") = 'C'. Dereferencing a string gives you a char, not a substring
– MSalters
Sep 21 '09 at 10:34
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show 15 mo...
How to select rows with one or more nulls from a pandas DataFrame without listing columns explicitly
... 0.0 NaN 0.0
3 0.0 1.0 2.0 3.0
4 NaN 0.0 NaN NaN
If you want to select the rows that have two or more columns with null value, you run the following:
>>> qty_of_nuls = 2
>>> df.iloc[df[(df.isnull().sum(axis=1) >=qty_of_nuls)].index]
0 1 2 3
1 0.0 NaN 0...
Use LINQ to get items in one List, that are not in another List
...erride the equality:
var excludedIDs = new HashSet<int>(peopleList1.Select(p => p.ID));
var result = peopleList2.Where(p => !excludedIDs.Contains(p.ID));
This variant does not remove duplicates.
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Convert an image (selected by path) to base64 string
How do you convert an image from a path on the user's computer to a base64 string in C#?
12 Answers
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How do I pass JavaScript variables to PHP?
...larieids">SalarieID:</label>
<?php
$query = "SELECT * FROM salarie";
$result = mysql_query($query);
if ($result) :
?>
<select id="salarieids" name="salarieid">
<?php
while ($row = mysql_fetch_assoc($r...
C#/Linq: Apply a mapping function to each element in an IEnumerable?
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You can just use the Select() extension method:
IEnumerable<int> integers = new List<int>() { 1, 2, 3, 4, 5 };
IEnumerable<string> strings = integers.Select(i => i.ToString());
Or in LINQ syntax:
IEnumerable<int> in...