title: finding the mean of columns in a data frame in R
body: <p>I have a vector that contains 50 data frames of re-sampled data. So all of the column names are consistent in each data frame but the numeric values are different. Each data frame consists of 12 rows. How can I find the mean value of each row in one particular column between the 50 data frames and place the 12 mean values into a new one column data frame?  </p>