Skip to contents

Create a daily aggregation from an hourly dataset

Source: R/table_aggregation.R
daily_aggregation.Rd

https://confluence.ecmwf.int/display/CKB/ERA5+family+post-processed+daily+statistics+documentation # nolint: line_length_linter

Usage

daily_aggregation(
  folder_in,
  folder_out,
  pattern = ".txt$",
  from = "2002-01-01 00",
  to = "2021-05-31 23",
  drop_first_record = TRUE,
  aggregation_function = mean,
  mode = c("agg_fun", "max_min", "value_at_hour")[1],
  value_hour = 0,
  na.rm = FALSE
)

Arguments

folder_in

Path of the input files

folder_out

Path where to save the transformed files

pattern

an optional regular expression. Only file names which match the regular expression will be returned.

from

The first date of the series, including the hour part.

to

The last date of the series, including the hour part.

drop_first_record

Logical. If TRUE, the first row of each input file is removed before the date sequence is assigned. This is useful when the input file contains a leading 00:00 record that belongs to the previous day and should not be part of the requested from/to range. After this optional removal, the number of rows in each input file must match the number of hours between from and to.

aggregation_function

The function to use on the hourly groups like mean, sum, mode, etc

mode

The mode of aggregation. The options are agg_fun, max_min or value_at_hour.

value_hour

Integer hour between 0 and 23 used when mode = "value_at_hour". The default is 0, which matches products whose daily accumulated value is timestamped at 00:00 at the end of the accumulation period. In this case, users should include the following day's 00:00 record in the requested period.

na.rm

a logical value indicating whether NA values should be removed before the computation proceeds.

Value

Files with a daily resolution

Details

This function allows to aggregate hourly observations to daily time series. The function for aggregation can be informed in the aggregation_function parameter, this parameter takes a function as argument. The default function is mean, so a daily average is returned.

The function will create a daily aggregation from an hourly dataset. The function for aggregation can be informed in the aggregation_function parameter, this parameter takes a function as argument. The default function is mean, so a daily average is returned. Alternatively, the user can choose the mode parameter to inform the function to use choosing between the agg_fun, max_min, and value_at_hour. The agg_fun will use the function informed in the aggregation_function parameter. The max_min will return the maximum and minimum values of the day. The value_at_hour mode will return the value timestamped at value_hour. For daily accumulated products timestamped at 00:00, set mode = "value_at_hour", keep value_hour = 0, and define from/to so that the 00:00 record ending the accumulation period is included. Use drop_first_record = TRUE only when the file also contains an extra leading row that must be discarded before assigning this date range.