mean data frame columns by group R

To mean data frame columns by group in Perl, you can use the groupby function from the List::UtilsBy module. Here's an example:

use strict;
use warnings;
use List::UtilsBy qw( group_by );

# Sample data
my @data = (
    { group => 'A', value => 10 },
    { group => 'A', value => 20 },
    { group => 'B', value => 30 },
    { group => 'B', value => 40 },
    { group => 'B', value => 50 }

# Group the data by 'group' column
my %grouped_data = group_by { $_->{group} } @data;

# Calculate the mean for each group
my %mean_by_group;
foreach my $group (keys %grouped_data) {
    my @values = map { $_->{value} } @{$grouped_data{$group}};
    my $mean = sum(@values) / scalar(@values);
    $mean_by_group{$group} = $mean;

# Print the mean for each group
foreach my $group (keys %mean_by_group) {
    print "Mean for group $group: $mean_by_group{$group}\n";

This code uses the group_by function to group the data by the 'group' column. Then, it calculates the mean for each group by summing up the values and dividing by the number of values. Finally, it prints the mean for each group.

Please note that Perl is not commonly used for data analysis and manipulation tasks like this. Other languages like R or Python are more commonly used for such tasks due to their extensive libraries and built-in support for data frames.