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?我已经为此进行了搜索，并且看到了很多函数(sum，cumsum，rowsum，rowSums，colSums，aggregate，apply)，但我无法理解所有内容.

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，假设我有一个包含以下列的数据框people

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

您可以只使用sum(people$Weight).

sum对向量求和，people$Weight从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-您可以使用?sum，?colSums等获得内置帮助(顺便说一句，colSums将为您提供每一列的总和).

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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