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Combine two or more columns in a dataframe into a new column with a new name
... already mentioned in comments by Uwe and UseR, a general solution in the tidyverse format would be to use the command unite:
library(tidyverse)
n = c(2, 3, 5)
s = c("aa", "bb", "cc")
b = c(TRUE, FALSE, TRUE)
df = data.frame(n, s, b) %>%
unite(x, c(n, s), sep = " ", remove = FALSE)
...
Tainted canvases may not be exported
...mage data from localStorage instead of loading from file or any url, then did some manipulation to it like adding a text. Then tried to sotre back it to localStorage using toDataURL(). But it shows "Failed to execute 'toDataURL' on 'HTMLCanvasElement': Tainted canvases may not be exported". In this ...
What's the difference between a 302 and a 307 redirect?
...he 307 Internal Redirect in action is when Google Chrome encounters a HTTP call to a domain it knows as requiring Strict Transport Security.
The browser redirects seamlessly, using the same method as the original call.
sh...
Difference between static and shared libraries?
...t with ... functionally equivalent, but may [improve] performance": specifically, equivalent caller-facing functionality in semantic use of the API (application programming interface: function signatures and variables including types), but implementation-side functionality may differ in more than pe...
Variable declaration placement in C
...ion 1, may times you can only get the initial value later in the block, by calling another function, or performing a caclulation, may be.
– Plumenator
May 20 '11 at 12:03
4
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Assign an initial value to radio button as checked
...
@niksvp I believe checked="checked" is the valid way to pre-check a radio button - just using "checked" isn't valid HTML (despite being supported by most browsers)
– Matt Healy
Jan 17 '11 at 9:36
...
Why doesn't Java support unsigned ints?
... it depends on the domain, but there is a reason why positive integers are called natural numbers ;-) ).
– Luc Touraille
Jun 27 '11 at 8:27
15
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How to test multiple variables against a value?
... You cannot iterate a dictionary this way: you are missing .keys() call. Also, it would be simpler just to use a string "cdef" instead of a dictionary here. Other than that, I don't see any value in your answer.
– VisioN
2 days ago
...
Is there a regular expression to detect a valid regular expression?
...titutions and translations. s/<this part>/.../
It is not theoretically possible to match all valid regex grammars with a regex.
It is possible if the regex engine supports recursion, such as PCRE, but that can't really be called regular expressions any more.
Indeed, a "recursive reg...
Draw Circle using css alone [duplicate]
...
Yep, draw a box and give it a border radius that is half the width of the box:
#circle {
background: #f00;
width: 200px;
height: 200px;
border-radius: 50%;
}
Working demo:
http://jsfiddle.net/DsW9h/1/
#circle {
background: #f00;
width: 200px;
heig...