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Remove columns from dataframe where ALL values are NA
...m.time({df1 <- bd[,colSums(is.na(bd) < nrow(bd))]})
# error -- can't allocate vector of size ...
system.time({df2 <- bd[, !apply(is.na(bd), 2, all)]})
# error -- can't allocate vector of size ...
system.time({df3 <- Filter(function(x)!all(is.na(x)), bd)})
## user system elapsed
## 0.26...
What's the difference between isset() and array_key_exists()? [duplicate]
...t will return false when the array value is set to null.
See isset on the PHP documentation site.
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Remove URL parameters without refreshing page
...m/old-page-name => can become => www.example.com/myNewPaage20180322.php
Background
We can use:
1- The pushState() method if you want to add a new modified URL to history entries.
2- The replaceState() method if you want to update/replace current history entry.
.replaceState() operate...
How to draw a custom UIView that is just a circle - iPhone app
... could use QuartzCore and do something this --
self.circleView = [[UIView alloc] initWithFrame:CGRectMake(10,20,100,100)];
self.circleView.alpha = 0.5;
self.circleView.layer.cornerRadius = 50; // half the width/height
self.circleView.backgroundColor = [UIColor blueColor];
...
PHP sprintf escaping %
....new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f3666734%2fphp-sprintf-escaping%23new-answer', 'question_page');
}
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How can I scan barcodes on iOS?
...tWithDevice:self.device error:nil];
self.session = [[AVCaptureSession alloc] init];
self.output = [[AVCaptureMetadataOutput alloc] init];
[self.session addOutput:self.output];
[self.session addInput:self.input];
[self.output setMetadataObjectsDelegate:self queue:dispatch_get_m...
Increase heap size in Java
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It is possible to increase heap size allocated by the JVM by using command line options
Here we have 3 options
-Xms<size> set initial Java heap size
-Xmx<size> set maximum Java heap size
-Xss<size> set java thread stack si...
How can I get the current page's full URL on a Windows/IIS server?
...to a new folder on a Windows/ IIS server. I'm setting up 301 redirects in PHP, but it doesn't seem to be working. My post URLs have the following format:
...
Find out how much memory is being used by an object in Python [duplicate]
... different implementation for small number of keys and sometimes they over allocate entries).
There is a big chunk of code (and an updated big chunk of code) out there to try to best approximate the size of a python object in memory.
You may also want to check some old description about PyObject ...
How to store values from foreach loop into an array?
... Declaring $items = array(); before foreach is not even necessary, right? php will just create an empty array
– BassMHL
Oct 2 '17 at 2:25
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