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Clojure: cons (seq) vs. conj (list)
...guments to insert into a collection, while cons takes just one:
(conj '(1 2 3) 4 5 6)
; => (6 5 4 1 2 3)
(cons 4 5 6 '(1 2 3))
; => IllegalArgumentException due to wrong arity
Another difference is in the class of the return value:
(class (conj '(1 2 3) 4))
; => clojure.lang.Persistent...
Grep regex NOT containing string
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answered May 2 '12 at 10:10
beerbajaybeerbajay
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Emulate ggplot2 default color palette
What function can I use to emulate ggplot2's default color palette for a desired number of colors. For example, an input of 3 would produce a character vector of HEX colors with these colors:
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How to add new item to hash
...eate the hash:
hash = {:item1 => 1}
Add a new item to it:
hash[:item2] = 2
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How to get Scala List from Java List?
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EDIT: Note that this is deprecated since 2.12.0. Use JavaConverters instead. (comment by @Yaroslav)
Since Scala 2.8 this conversion is now built into the language using:
import scala.collection.JavaConversions._
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lst.toList.foreach{ node => .... }
works. ...
How to reorder data.table columns (without copying)
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2 Answers
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R - Concatenate two dataframes?
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227
You want "rbind".
b$b <- NA
new <- rbind(a, b)
rbind requires the data frames to have...
How would I get a cron job to run every 30 minutes?
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edited Sep 27 '11 at 13:45
Tim Cooper
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Unicode与UTF-8互转(C语言实现) - C/C++ - 清泛网 - 专注C/C++及内核技术
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位(bit)有0和1两种状态, 因此八个二进制位就可以组合出 256种状态, 这被称为一个字
节(byte). 也就是说, 一个字节一共可以用来表示256种不同的状态, 每一个状态对应一
个符号, 就是256个符号, 从 0000000到11111111.
上个世纪60年代...
How can I create a Set of Sets in Python?
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121
Python's complaining because the inner set objects are mutable and thus not hashable. The solut...