June 2020
Beginner to intermediate
522 pages
9h 6m
Chinese
Content preview from R 语言经典实例（原书第 2 版）
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362
｜
第
12
章
12.3 对行和列求和
12.3.1 问题
需要对矩阵或数据框的行或列求和。
12.3.2 解决方案
使用 rowSums 函数对行进行求和：
rowSums(
m
)
使用 colSums 函数对列进行求和：
colSums(
m
)
12.3.3 讨论
这是一个简单的方法，但它非常常见，值得一提。例如，在生成包含列总和的汇总报告
时，我们使用此方法。在这个例子中，daily.prod 是本周工厂生产的记录，我们希望
按产品和天计算总和：
load(file = './data/daily.prod.rdata')
daily.prod
#> Widgets Gadgets Thingys
#> Mon 179 167 182
#> Tue 153 193 166
#> Wed 183 190 170
#> Thu 153 161 171
#> Fri 154 181 186
colSums(daily.prod)
#> Widgets Gadgets Thingys
#> 822 892 875
rowSums(daily.prod)
#> Mon Tue Wed Thu Fri
#> 528 512 543 485 521
这些函数返回一个向量。在有列总和的情况下，我们可以将和向量附加到矩阵，从而整
齐地打印原始数据和总和：
rbind(daily.prod, Totals=colSums(daily.prod))
#> Widgets Gadgets Thingys
#> Mon 179 167 182
#> Tue ...
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