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.
我有一个数据框架，有几个列;一些数字和一些字符。如何计算某一列的和?我用谷歌搜索了一下，看到了很多函数(sum、cumsum、rowsum、rowsum、colsum、aggregate、apply)，但我搞不懂。
For example suppose I have a data frame people with the following columns
例如，假设我有一个具有以下列的数据框架人员
Name Height Weight
Mary 65 110
John 70 200
Jane 64 115
…
How do I get the sum of all the weights?
如何得到所有权重的和?
1 个解决方案
#1
63
You can just use sum(people$Weight).
你可以用sum(人$Weight)。
sum sums up a vector, and people$Weight retrieves the weight column from your data frame.
sum汇总一个向量，people$Weight从您的数据帧中检索权重列。
Note - you can get built-in help by using ?sum, ?colSums, etc. (by the way, colSums will give you the sum for each column).
注:您可以通过使用?sum、? colsum等获得内置帮助(顺便说一下，colsum将为您提供每一列的总和)。
#1
63
You can just use sum(people$Weight).
你可以用sum(人$Weight)。
sum sums up a vector, and people$Weight retrieves the weight column from your data frame.
sum汇总一个向量，people$Weight从您的数据帧中检索权重列。
Note - you can get built-in help by using ?sum, ?colSums, etc. (by the way, colSums will give you the sum for each column).
注:您可以通过使用?sum、? colsum等获得内置帮助(顺便说一下，colsum将为您提供每一列的总和)。