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Sample random rows in dataframe
...propriate function that would return a specified number of rows picked up randomly without replacement from a data frame in R language? Can anyone help me out?
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Wrapping a C library in Python: C, Cython or ctypes?
...Python application. I don't want to wrap the whole API, only the functions and datatypes that are relevant to my case. As I see it, I have three choices:
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Structs versus classes
...e small ones, only with 2 or 3 properties. I'll put them in a generic list and when they are, I'll loop them and check value a and maybe update value b .
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“PKIX path building failed” and “unable to find valid certification path to requested target”
...got an error about certificate sun.security.validator.ValidatorException and sun.security.provider.certpath.SunCertPathBuilderException . Then I added twitter certificate by:
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Resize image in PHP
...0, 0, 0, 0, $newwidth, $newheight, $width, $height);
return $dst;
}
And you could call this function, like so...
$img = resize_image(‘/path/to/some/image.jpg’, 200, 200);
From personal experience, GD's image resampling does dramatically reduce file size too, especially when resampling ...
C libcurl get output into a string
...de that passes a buffer struct string {*ptr; len} to the callback function and grows that buffer on each call using realloc().
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <curl/curl.h>
struct string {
char *ptr;
size_t len;
};
void init_string(s...
Multiple queries executed in java in single statement
...c.. Acceptable values for allowMultiQueries property are true, false, yes, and no. Any other value is rejected at runtime with an SQLException.
String dbUrl = "jdbc:mysql:///test?allowMultiQueries=true";
Unless such instruction is passed, an SQLException is thrown.
You have to use execute( S...
get keys of json-object in JavaScript [duplicate]
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I am trying to convert rows from DB to JSON. I am getting numerical index along with actual column names as keys. Why I am getting numerical index?
– Nguai al
Jul 24 at 16:41
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How do I trim a file extension from a String in Java?
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Handle with care: it'll throw an Exception at you if the file name has no suffix.
– Andreas Dolk
Jun 2 '09 at 22:44
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Does Java SE 8 have Pairs or Tuples?
I am playing around with lazy functional operations in Java SE 8, and I want to map an index i to a pair / tuple (i, value[i]) , then filter based on the second value[i] element, and finally output just the indices.
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