Mean per group in a data.frame
55747
Grouping functions (tapply, by, aggregate) and the *apply family
12545
Calculate first difference by group in R
117343
Average of multiple columns
149640
calculate the mean of trials for each subject in R
139710
How do I combine standard deviations of two groups?
121414
Aggregate data in R
158254
Calculating distribution from min, mean, and max
103595
Pandas group by operations on a data frame
51764
python groupby behaviour?
24411
Aggregate / summarize multiple variables per group (e.g. sum, mean)
117810
Transform Data to Desired Mean and Standard Deviation
136871
R use ddply or aggregate
6493
Repeat each row of data.frame the number of times specified in a column
689
Using LIMIT within GROUP BY to get N results per group?
86329
Filter data.frame rows by a logical condition
36003
Summarizing multiple columns with data.table
118871
Testing whether the mean of a group is different from the mean of the entire sample