sparklyr.flint (version 0.2.2)

summarize_var: Variance summarizer

Description

Compute variance of values from `column` within each time window or within each group of records with identical timestamps, and store results in a new column named `<column>_variance`, with Bessel's correction applied to the results

Usage

summarize_var(ts_rdd, column, window = NULL, key_columns = list())

Arguments

ts_rdd

Timeseries RDD being summarized

column

Column to be summarized

window

Either an R expression specifying time windows to be summarized (e.g., `in_past("1h")` to summarize data from looking behind 1 hour at each time point, `in_future("5s")` to summarize data from looking forward 5 seconds at each time point), or `NULL` to compute aggregate statistics on records grouped by timestamps

key_columns

Optional list of columns that will form an equivalence relation associating each record with the time series it belongs to (i.e., any 2 records having equal values in those columns will be associated with the same time series, and any 2 records having differing values in those columns are considered to be from 2 separate time series and will therefore be summarized separately) By default, `key_colums` is empty and all records are considered to be part of a single time series.

Value

A TimeSeriesRDD containing the summarized result

See Also

Other summarizers: ols_regression(), summarize_avg(), summarize_corr2(), summarize_corr(), summarize_count(), summarize_covar(), summarize_dot_product(), summarize_ema_half_life(), summarize_ewma(), summarize_geometric_mean(), summarize_kurtosis(), summarize_max(), summarize_min(), summarize_nth_central_moment(), summarize_nth_moment(), summarize_product(), summarize_quantile(), summarize_skewness(), summarize_stddev(), summarize_sum(), summarize_weighted_avg(), summarize_weighted_corr(), summarize_weighted_covar(), summarize_z_score()

Examples

# NOT RUN {
library(sparklyr)
library(sparklyr.flint)

sc <- try_spark_connect(master = "local")

if (!is.null(sc)) {
  sdf <- copy_to(sc, tibble::tibble(t = seq(10), v = seq(10)))
  ts <- fromSDF(sdf, is_sorted = TRUE, time_unit = "SECONDS", time_column = "t")
  ts_var <- summarize_var(ts, column = "v", window = in_past("3s"))
} else {
  message("Unable to establish a Spark connection!")
}

# }