Skip to contents

Generate a draft validation plan in a new .R or .Rmd file using an input data table. Using this workflow, the data table will be scanned to learn about its column data and a set of starter validation steps (constituting a validation plan) will be written. It's best to use a data extract that contains at least 1000 rows and is relatively free of spurious data.

Once in the file, it's possible to tweak the validation steps to better fit the expectations to the particular domain. While column inference is used to generate reasonable validation plans, it is difficult to infer the acceptable values without domain expertise. However, using draft_validation() could get you started on floor 10 of tackling data quality issues and is in any case better than starting with an empty code editor view.

Usage

draft_validation(
  tbl,
  tbl_name = NULL,
  file_name = tbl_name,
  path = NULL,
  lang = NULL,
  output_type = c("R", "Rmd"),
  add_comments = TRUE,
  overwrite = FALSE,
  quiet = FALSE
)

Arguments

tbl

The input table. This can be a data frame, tibble, a tbl_dbi object, or a tbl_spark object.

tbl_name

A optional name to assign to the input table object. If no value is provided, a name will be generated based on whatever information is available. This table name will be displayed in the header area of the agent report generated by printing the agent or calling get_agent_report().

file_name

An optional name for the .R or .Rmd file. This should be a name without an extension. By default, this is taken from the tbl_name but if nothing is supplied for that, the name will contain the text "draft_validation_" followed by the current date and time.

path

A path can be specified here if there shouldn't be an attempt to place the generated file in the working directory.

lang

The language to use when creating comments for the automatically- generated validation steps. By default, NULL will create English ("en") text. Other options include French ("fr"), German ("de"), Italian ("it"), Spanish ("es"), Portuguese ("pt"), Turkish ("tr"), Chinese ("zh"), Russian ("ru"), Polish ("pl"), Danish ("da"), Swedish ("sv"), and Dutch ("nl").

output_type

An option for choosing what type of output should be generated. By default, this is an .R script ("R") but this could alternatively be an R Markdown document ("Rmd").

add_comments

Should there be comments that explain the features of the validation plan in the generated document? By default, this is TRUE.

overwrite

Should a file of the same name be overwritten? By default, this is FALSE.

quiet

Should the function not inform when the file is written? By default this is FALSE.

Value

Invisibly returns TRUE if the file has been written.

Supported Input Tables

The types of data tables that are officially supported are:

Other database tables may work to varying degrees but they haven't been formally tested (so be mindful of this when using unsupported backends with pointblank).

Examples

Let's draft a validation plan for the dplyr::storms dataset.

dplyr::storms

## # A tibble: 11,859 × 13
##    name   year month   day  hour   lat  long status      category  wind pressure
##    <chr> <dbl> <dbl> <int> <dbl> <dbl> <dbl> <chr>       <ord>    <int>    <int>
##  1 Amy    1975     6    27     0  27.5 -79   tropical d… -1          25     1013
##  2 Amy    1975     6    27     6  28.5 -79   tropical d… -1          25     1013
##  3 Amy    1975     6    27    12  29.5 -79   tropical d… -1          25     1013
##  4 Amy    1975     6    27    18  30.5 -79   tropical d… -1          25     1013
##  5 Amy    1975     6    28     0  31.5 -78.8 tropical d… -1          25     1012
##  6 Amy    1975     6    28     6  32.4 -78.7 tropical d… -1          25     1012
##  7 Amy    1975     6    28    12  33.3 -78   tropical d… -1          25     1011
##  8 Amy    1975     6    28    18  34   -77   tropical d… -1          30     1006
##  9 Amy    1975     6    29     0  34.4 -75.8 tropical s… 0           35     1004
## 10 Amy    1975     6    29     6  34   -74.8 tropical s… 0           40     1002
## # … with 11,849 more rows, and 2 more variables:
## #   tropicalstorm_force_diameter <int>, hurricane_force_diameter <int>

The draft_validation() function creates an .R file by default. Using just the defaults with dplyr::storms will yield the "dplyr__storms.R" file in the working directory. Here are the contents of the file:

library(pointblank)

agent <-
  create_agent(
    tbl = ~ dplyr::storms,
    actions = action_levels(
      warn_at = 0.05,
      stop_at = 0.10
    ),
    tbl_name = "dplyr::storms",
    label = "Validation plan generated by `draft_validation()`."
  ) %>%
  # Expect that column `name` is of type: character
  col_is_character(
    columns = vars(name)
  ) %>%
  # Expect that column `year` is of type: numeric
  col_is_numeric(
    columns = vars(year)
  ) %>%
  # Expect that values in `year` should be between `1975` and `2020`
  col_vals_between(
    columns = vars(year),
    left = 1975,
    right = 2020
  ) %>%
  # Expect that column `month` is of type: numeric
  col_is_numeric(
    columns = vars(month)
  ) %>%
  # Expect that values in `month` should be between `1` and `12`
  col_vals_between(
    columns = vars(month),
    left = 1,
    right = 12
  ) %>%
  # Expect that column `day` is of type: integer
  col_is_integer(
    columns = vars(day)
  ) %>%
  # Expect that values in `day` should be between `1` and `31`
  col_vals_between(
    columns = vars(day),
    left = 1,
    right = 31
  ) %>%
  # Expect that column `hour` is of type: numeric
  col_is_numeric(
    columns = vars(hour)
  ) %>%
  # Expect that values in `hour` should be between `0` and `23`
  col_vals_between(
    columns = vars(hour),
    left = 0,
    right = 23
  ) %>%
  # Expect that column `lat` is of type: numeric
  col_is_numeric(
    columns = vars(lat)
  ) %>%
  # Expect that values in `lat` should be between `-90` and `90`
  col_vals_between(
    columns = vars(lat),
    left = -90,
    right = 90
  ) %>%
  # Expect that column `long` is of type: numeric
  col_is_numeric(
    columns = vars(long)
  ) %>%
  # Expect that values in `long` should be between `-180` and `180`
  col_vals_between(
    columns = vars(long),
    left = -180,
    right = 180
  ) %>%
  # Expect that column `status` is of type: character
  col_is_character(
    columns = vars(status)
  ) %>%
  # Expect that column `category` is of type: factor
  col_is_factor(
    columns = vars(category)
  ) %>%
  # Expect that column `wind` is of type: integer
  col_is_integer(
    columns = vars(wind)
  ) %>%
  # Expect that values in `wind` should be between `10` and `160`
  col_vals_between(
    columns = vars(wind),
    left = 10,
    right = 160
  ) %>%
  # Expect that column `pressure` is of type: integer
  col_is_integer(
    columns = vars(pressure)
  ) %>%
  # Expect that values in `pressure` should be between `882` and `1022`
  col_vals_between(
    columns = vars(pressure),
    left = 882,
    right = 1022
  ) %>%
  # Expect that column `tropicalstorm_force_diameter` is of type: integer
  col_is_integer(
    columns = vars(tropicalstorm_force_diameter)
  ) %>%
  # Expect that values in `tropicalstorm_force_diameter` should be between `0` and `870`
  col_vals_between(
    columns = vars(tropicalstorm_force_diameter),
    left = 0,
    right = 870,
    na_pass = TRUE
  ) %>%
  # Expect that column `hurricane_force_diameter` is of type: integer
  col_is_integer(
    columns = vars(hurricane_force_diameter)
  ) %>%
  # Expect that values in `hurricane_force_diameter` should be between `0` and `300`
  col_vals_between(
    columns = vars(hurricane_force_diameter),
    left = 0,
    right = 300,
    na_pass = TRUE
  ) %>%
  # Expect entirely distinct rows across all columns
  rows_distinct() %>%
  # Expect that column schemas match
  col_schema_match(
    schema = col_schema(
      name = "character",
      year = "numeric",
      month = "numeric",
      day = "integer",
      hour = "numeric",
      lat = "numeric",
      long = "numeric",
      status = "character",
      category = c("ordered", "factor"),
      wind = "integer",
      pressure = "integer",
      tropicalstorm_force_diameter = "integer",
      hurricane_force_diameter = "integer"
    )
  ) %>%
  interrogate()

agent

This is runnable as is, and the promise is that the interrogation should produce no failing test units. After execution, we get the following validation report:

All of the expressions in the resulting file constitute just a rough approximation of what a validation plan should be for a dataset. Certainly, the value ranges in the emitted col_vals_between() may not be realistic for the wind column and may require some modification (the provided left and right values are just the limits of the provided data). However, note that the lat and long (latitude and longitude) columns have acceptable ranges (providing the limits of valid lat/lon values). This is thanks to pointblank's column inference routines, which is able to understand what certain columns contain.

For an evolving dataset that will experience changes (either in the form of revised data and addition/deletion of rows or columns), the emitted validation will serve as a good first step and changes can more easily be made since there is a foundation to build from.

Function ID

1-11

See also