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What is Weak Head Normal Form?
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These expressions are all in normal form:
42
(2, "hello")
\x -> (x + 1)
These expressions are not in normal form:
1 + 2 -- we could evaluate this to 3
(\x -> x + 1) 2 -- we could apply the function
"he" ++ "llo" -- we could apply the (++)
(1 + 1, 2 + 2) ...
Why do Lua arrays(tables) start at 1 instead of 0?
...ionale behind the decision of this part of Lua. Why does indexing start at 1? I have read (as many others did) this great paper . It seems to me a strange corner of a language that is very pleasant to learn and program. Don't get me wrong, Lua is just great but there has to be an explanation somewh...
How can I setup & run PhantomJS on Ubuntu?
...ntomJS and recorded it to video: https://www.dailymotion.com/video/xnizmh_1_webcam
25 Answers
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How to show all shared libraries used by executables in Linux?
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13 Answers
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How to assign from a function which returns more than one value?
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Can dplyr package be used for conditional mutating?
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Use ifelse
df %>%
mutate(g = ifelse(a == 2 | a == 5 | a == 7 | (a == 1 & b == 4), 2,
ifelse(a == 0 | a == 1 | a == 4 | a == 3 | c == 4, 3, NA)))
Added - if_else: Note that in dplyr 0.5 there is an if_else function defined so an alternative would be to replace ifelse with i...
Convert RGB to RGBA over white
I have a hex color, e.g. #F4F8FB (or rgb(244, 248, 251) ) that I want converted into an as-transparent-as-possible rgba color (when displayed over white). Make sense? I'm looking for an algorithm, or at least idea of an algorithm for how to do so.
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How do I represent a hextile/hex grid in memory?
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Amit Patel has posted an amazing page on this topic. It's so comprehensive and wonderful that ...
Decreasing for loops in Python impossible?
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for n in range(6,0,-1):
print n
# prints [6, 5, 4, 3, 2, 1]
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