如何对 data.frame 列值求和? [英] How to sum data.frame column values?

问题描述

我有一个包含几列的数据框；一些数字和一些字符.如何计算特定列的总和?我已经为此搜索过很多函数(sum、cumsum、rowsum, rowSums, colSums, aggregate, apply) 但我无法理解这一切.

I have a data frame with several columns; some numeric and some character. How to compute the sum of a specific column? I’ve googled for this and I see numerous functions (sum, cumsum, rowsum, rowSums, colSums, aggregate, apply) but I can’t make sense of it all.

例如，假设我有一个数据框 people 包含以下列

For example suppose I have a data frame people with the following columns

people <- read(
  text = 
    "Name Height Weight
    Mary 65     110
    John 70     200
    Jane 64     115", 
  header = TRUE
)
…

如何获得所有权重的总和?

How do I get the sum of all the weights?

推荐答案

你可以使用 sum(people$Weight).

sum 对向量求和，people$Weight 从您的数据框中检索权重列.

sum sums up a vector, and people$Weight retrieves the weight column from your data frame.

注意 - 您可以通过使用 ?sum、?colSums 等获得内置帮助(顺便说一下，colSums 将给你每列的总和).

Note - you can get built-in help by using ?sum, ?colSums, etc. (by the way, colSums will give you the sum for each column).

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