summarise

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Summarise a data frame.

Summarise works in an analogous way to mutate, except instead of adding columns to an existing data frame, it creates a new data frame. This is particularly useful in conjunction with ddply as it makes it easy to perform group-wise summaries.

Keywords
manip
Usage
summarise(.data, ...)
Arguments
.data
the data frame to be summarised
...
further arguments of the form var = value
Note

Be careful when using existing variable names; the corresponding columns will be immediately updated with the new data and this can affect subsequent operations referring to those variables.

Aliases
  • summarise
  • summarize
Examples
library(plyr) # Let's extract the number of teams and total period of time # covered by the baseball dataframe summarise(baseball, duration = max(year) - min(year), nteams = length(unique(team))) # Combine with ddply to do that for each separate id ddply(baseball, "id", summarise, duration = max(year) - min(year), nteams = length(unique(team)))
Documentation reproduced from package plyr, version 1.8.4, License: MIT + file LICENSE

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