How to sum data frame column values

Question

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  people  lt - read    text         Name Height Weight     Mary 65     110     John 70     200     Jane 64     115      header   TRUE         How do I get the sum of all the weights

User · Answer

to order after the colsum    order colSums people  decreasing TRUE    if more than 20  columns  order colSums people  c 5 25   decreasing TRUE    in case of keeping the first 4 columns remaining

User · Answer

When you have  NA  values in the column  then   sum as numeric JuneData1 Account Balance   na rm   TRUE

User · Answer

You can just use sum people Weight    sum sums up a vector  and people Weight retrieves the weight column from your data frame   Note - you can get built-in help by using  sum   colSums  etc   by the way  colSums will give you the sum for each column

User · Answer

To sum values in data frame you first need to extract them as a vector    There are several way to do it        operatior x  lt - people Weight x    1  65 70 64   Or using      similar to matrix   x  lt - people    Weight   x    1  65 70 64   Once you have the vector you can use any vector-to-scalar function to aggregate the result   sum people    Weight       1  199   If you have NA values in your data  you should specify na rm parameter   sum people    Weight    na rm   TRUE

[r] How to sum data.frame column values?

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