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Add Attributes to Columns

Source: R/cb_add_col_attributes.R
cb_add_col_attributes.Rd

Add arbitrary attributes to columns (e.g., description, source, column type). These attributes can later be accessed to fill in the column attributes table.

Usage

cb_add_col_attributes(df, .x, ...)

Arguments

df

Data frame of interest

.x

Column of interest in df

...

Arbitrary list of attributes (i.e., attribute = "value")

Value

Returns the same data frame (or tibble) passed to the df argument with column attributes added.

Details

Typically, though not necessarily, the first step in creating your codebook will be to add column attributes to your data. The cb_add_col_attributes() function is a convenience function that allows you to add arbitrary attributes to the columns of the data frame. These attributes can later be accessed to fill in the column attributes table of the codebook document. Column attributes can serve a similar function to variable labels in SAS or Stata; however, you can assign many different attributes to a column and they can contain any kind of information you want.

Although the cb_add_col_attributes() function will allow you to add any attributes you want, there are currently only five special attributes that the codebook() function will recognize and add to the column attributes table of the codebook document. They are:

description:

Although you may add any text you desire to the description attribute, it is intended to be used describe the question/process that generated the data contained in the column. Many statistical software packages refer to this as a variable label. If the data was imported from SAS, Stata, or SPSS with variable labels using the haven package, codebook will automatically recognize them. There is no need to manually create them. However, you may overwrite the imported variable label for any column by adding a description attribute.

source:

Although you may add any text you desire to the source attribute, it is intended to be used describe where the data contained in the column originally came from. For example, if the current data frame was created by merging multiple data sets together, you may want to use the source attribute to identify the data set it originates from. As another example, if the current data frame contains longitudinal data, you may want to use the source attribute to identify the wave(s) in which data for this column was collected.

col_type:

The col_type attribute is intended to provide additional information above and beyond the Data type (i.e., column class) about the values in the column. For example, you may have a column of 0's and 1's, which will have a numeric data type. However, you may want to inform data users that this is really a dummy variable where the 0's and 1's represent discrete categories (No and Yes). Another way to think about it is that the Data type attribute is how R understands the column and the Column type attribute is how humans should understand the column. Currently accepted values are:

  • Numeric

  • Categorical

  • Time

Perhaps even more importantly, setting the col_type attribute helps R determine which descriptive statistics to calculate for the bottom half of the column attributes table. Inside of the codebook() function, the cb_add_summary_stats() function will attempt to figure out whether the column is:

  • numeric

  • categorical - many categories (e.g. participant id)

  • categorical - few categories (e.g. sex)

  • time - including dates

Again, this matters because the table of summary stats shown in the codebook document depends on the value cb_add_summary_stats() chooses. However, the user can directly tell cb_add_summary_stats() which summary stats to calculate by providing a col_type attribute to a column with one of the following values: Numeric, Categorical, or Time.

value_labels:

Although you may pass any named vector you desire to the value_labels attribute, it is intended to inform your data users about how to correctly interpret numerically coded categorical variables. For example, you may have a column of 0's and 1's that represent discrete categories (i.e., "No" and "Yes") instead of numerical quantities. In many other software packages (e.g., SAS, Stata, and SPSS), you can layer "No" and "Yes" labels on top of the 0's and 1's to improve the readability of your analysis output. These are commonly referred to as value labels. The R programming language does not really have value labels in the same way that other popular statistical software applications do. R users can (and typically should) coerce numerically coded categorical variables into factors; however, coercing a numeric vector to a factor is not the same as adding value labels to a numeric vector because the underlying numeric values can change in the process of creating the factor. For this, and other reasons, many R programmers choose to create a new factor version of a numerically encoded variable as opposed to overwriting/transforming the numerically encoded variable. In those cases, you may want to inform your data users about how to correctly interpret numerically coded categorical variables. Adding value labels to your codebook is one way of doing so.

  • Add value labels to columns as a named vector to the value_labels attribute. For example, value_labels = c("No" = 0, "Yes" = 1).

  • If the data was imported from SAS, Stata, or SPSS with value labels using the haven package, codebook will automatically recognize them. There is no need to manually create them. However, you may overwrite the imported value labels for any column by adding a value_labels attribute as shown in the example below.

skip_pattern:

Although you may add any text you desire to the skip_pattern attribute, it is intended to be used describe skip patterns in the data collection tools that impact which study participants were exposed to each study item. For example, If a question in your data was only asked of participants who were enrolled in the study for at least 10 days, then you may want to add a note like "Not asked if days < 10" to the skip pattern section of the column attributes table.

Examples

library(dplyr, warn.conflicts = FALSE)
library(codebookr)
data(study)

study <- study %>%
  cb_add_col_attributes(
    .x = likert,
    description = "An example Likert scale item",
    source = "Exposure questionnaire",
    col_type = "categorical",
    value_labels = c(
      "Very dissatisfied" = 1,
      "Somewhat dissatisfied" = 2,
      "Neither satisfied nor dissatisfied" = 3,
      "Somewhat satisfied" = 4,
      "Very satisfied" = 5
    ),
    skip_pattern = "Not asked if days < 10"
  )
#> The following attribute(s) are being added to a variable in the data frame for the first time: description, source, col_type, value_labels, skip_pattern. If you believe this/these attribute(s) were previously added, then check for a typo in the attribute name. If you are adding this/these attribute(s) for the first time, you can probably safely ignore this message.