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How to get row from R data.frame
...for example:
#Add your data
x <- structure(list(A = c(5, 3.5, 3.25, 4.25, 1.5 ),
B = c(4.25, 4, 4, 4.5, 4.5 ),
C = c(4.5, 2.5, 4, 2.25, 3 )
),
.Names = c("A", "B", "C"),
class = "data.f...
Objective-C 2.0 Mac和iOS开发实践指南 PDF扫描版 - 文档下载 - 清泛网 - ...
...1. C程序的结构
1.1.1. main函数
1.1.2 格式化
1.1.3 注释
1.1.4 变量和函数名
1.1.5 命名惯例
1.1.6 文件
1.2 变量
1.2.1. 整数类型
1.2.2 浮点类型
1.2.3 真值
1.2.4 初始化
1.2.5 指针
1.2.6 数组
1.2.7 字符串
1.2.8 结构
1.2.9 typedef
1.2.10 枚...
Reorder levels of a factor without changing order of values
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Use the levels argument of factor:
df <- data.frame(f = 1:4, g = letters[1:4])
df
# f g
# 1 1 a
# 2 2 b
# 3 3 c
# 4 4 d
levels(df$g)
# [1] "a" "b" "c" "d"
df$g <- factor(df$g, levels = letters[4:1])
# levels(df$g)
# [1] "d" "c" "b" "a"
df
# f g
# 1 1 a
# 2 2 b
# 3 3 c
# 4 ...
List of lists changes reflected across sublists unexpectedly
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14 Answers
14
Active
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Assign multiple columns using := in data.table, by group
...b col1 col2
# 1: 1 1 hi hello
# 2: 2 2 hi hello
# 3: 3 3 hi hello
# 4: 1 4 hi hello
# 5: 2 5 hi hello
# 6: 3 6 hi hello
x[ , c("mean", "sum") := list(mean(b), sum(b)), by = a][]
# a b col1 col2 mean sum
# 1: 1 1 hi hello 2.5 5
# 2: 2 2 hi hello 3.5 7
# 3: 3 3 hi hello ...
All combinations of a list of lists
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449
you need itertools.product:
>>> import itertools
>>> a = [[1,2,3],[4,5,6],[...
SQL Logic Operator Precedence: And and Or
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4 Answers
4
Active
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What is the significance of initializing direction arrays below with given values when developing ch
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84
This is a technique to encode all directions as arrays - every pair of di[i],dj[i] is a differen...
Clojure 1.2.1/1.3/1.4 'proxy generated in Grails 2.0.0 runtime fails. 1.2.0 is fine
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4
I found an Issue called CLJ-944 on clojure.org. There you can find a fix for ClassCastException:...