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.
For example, suppose I have a data frame people with the following columns
Name Height Weight
Mary 65 110
John 70 200
Jane 64 115
How do I get the sum of all the weights?