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setup cron tab to specific time of during weekdays
...server. We want the cron job to run the script at certain times of the day and on some specific days of the week. For example, we want to setup a cron job that runs the script with the following sequence:
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find() with nil when there are no records
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Yes, just do:
Challenge.find_by_id(10)
For Rails 4 and 5:
Challenge.find_by(id: 10)
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How do I draw a grid onto a plot in Python?
I just finished writing code to make a plot using pylab in Python and now I would like to superimpose a grid of 10x10 onto the scatter plot. How do I do that?
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How do you make a WPF slider snap only to discrete integer positions?
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The simple answer is that you take advantage of the IsSnapToTickEnabled and TickFrequency properties. That is, turn snapping to ticks on and set the tick frequency to 1.
Or, in other words ... take advantage of ticks ... but you don't necessarily have to show the ticks that you are snapping to.
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Call static method with reflection
...f the method resides in an ancestor class.
– J. Ouwehand
Jun 8 '19 at 14:51
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How do you return a JSON object from a Java Servlet
... it out to the response writer along with content type of application/json and character encoding of UTF-8.
Here's an example assuming you're using Google Gson to convert a Java object to a JSON string:
protected void doXxx(HttpServletRequest request, HttpServletResponse response) {
// ...
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How to get numbers after decimal point?
...On a Raspberry Pi this method x%1 was almost twice as fast as the x-int(x) and modf(x)[0] methods (the timings were 980ns, 1.39us, and 1.47us averaged over 1000000 runs). My value for x was always positive so I did not have to worry about that.
– coderforlife
J...
Extracting the last n characters from a string in R
...se R, but it's straight-forward to make a function to do this using substr and nchar:
x <- "some text in a string"
substrRight <- function(x, n){
substr(x, nchar(x)-n+1, nchar(x))
}
substrRight(x, 6)
[1] "string"
substrRight(x, 8)
[1] "a string"
This is vectorised, as @mdsumner point...
How do I extract a sub-hash from a hash?
...:d=>:D}
h1 = Hash[h1.to_a - h2.to_a] # => {:a=>:A, :c=>:C}
And if you want to patch that into the Hash class:
class Hash
def extract_subhash(*extract)
h2 = self.select{|key, value| extract.include?(key) }
self.delete_if {|key, value| extract.include?(key) }
h2
end
en...
Filter rows which contain a certain string
...mail in the comments above. You can use regular expressions for the second and subsequent arguments of filter like this:
dplyr::filter(df, !grepl("RTB",TrackingPixel))
Since you have not provided the original data, I will add a toy example using the mtcars data set. Imagine you are only intereste...