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Relative frequencies / proportions with dplyr
...n = n()) %>%
mutate(freq = n / sum(n))
# am gear n freq
# 1 0 3 15 0.7894737
# 2 0 4 4 0.2105263
# 3 1 4 8 0.6153846
# 4 1 5 5 0.3846154
From the dplyr vignette:
When you group by multiple variables, each summary peels off one level of the grouping. That makes ...
What causes a java.lang.ArrayIndexOutOfBoundsException and how do I prevent it?
...
300
Your first port of call should be the documentation which explains it reasonably clearly:
T...
How do I read / convert an InputStream into a String in Java?
...|
edited May 21 '18 at 13:09
Marko Zajc
14811 silver badge1313 bronze badges
answered Nov 21 '08 at 16:5...
Python, Matplotlib, subplot: How to set the axis range?
How can I set the y axis range of the second subplot to e.g. [0,1000] ?
The FFT plot of my data (a column in a text file) results in a (inf.?) spike so that the actual data is not visible.
...
Accessing localhost:port from Android emulator
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420
You can access your host machine with the IP address "10.0.2.2".
This has been designed in thi...
Check if an array is empty or exists
...
if (typeof image_array !== 'undefined' && image_array.length > 0) {
// the array is defined and has at least one element
}
Your problem may be happening due to a mix of implicit global variables and variable hoisting. Make sure you use var whenever declaring a variable:
<?php e...
How to wait in bash for several subprocesses to finish and return exit code !=0 when any subprocess
...ral subprocesses spawned from that script to finish and return exit code !=0 when any of the subprocesses ends with code !=0 ?
...
Convert string with commas to array
... JSON.parse("[" + string + "]");
This gives you an Array of numbers.
[0, 1]
If you use .split(), you'll end up with an Array of strings.
["0", "1"]
Just be aware that JSON.parse will limit you to the supported data types. If you need values like undefined or functions, you'd need to use ...
Regex to validate password strength
...itive look ahead assertions:
^(?=.*[A-Z].*[A-Z])(?=.*[!@#$&*])(?=.*[0-9].*[0-9])(?=.*[a-z].*[a-z].*[a-z]).{8}$
Rubular link
Explanation:
^ Start anchor
(?=.*[A-Z].*[A-Z]) Ensure string has two uppercase letters.
(?=.*[!@#$&*]) Ensure string ha...
How to reuse an ostringstream?
...lear, then seek the appropriate sequence to the begin:
s.clear();
s.seekp(0); // for outputs: seek put ptr to start
s.seekg(0); // for inputs: seek get ptr to start
That will prevent some reallocations done by str by overwriting whatever is in the output buffer currently instead. Results are like...