Visualize Imputed Values

Source: R/ggplot_na_imputations.R

Visualize the imputed values in a time series.

ggplot_na_imputations(
  x_with_na,
  x_with_imputations,
  x_with_truth = NULL,
  x_axis_labels = NULL,
  title = "Imputed Values",
  subtitle = "Visualization of missing value replacements",
  xlab = "Time",
  ylab = "Value",
  color_points = "steelblue",
  color_imputations = "indianred",
  color_truth = "seagreen3",
  color_lines = "lightslategray",
  shape_points = 16,
  shape_imputations = 18,
  shape_truth = 16,
  size_points = 1.5,
  size_imputations = 2.5,
  size_truth = 1.5,
  size_lines = 0.5,
  linetype = "solid",
  connect_na = TRUE,
  legend = TRUE,
  legend_size = 5,
  label_known = "known values",
  label_imputations = "imputed values",
  label_truth = "ground truth",
  theme = ggplot2::theme_linedraw()
)

Arguments

x_with_na

Numeric Vector or Time Series (ts) object with NAs before imputation. This parameter and x_with_imputation shave to be set. The rest of the parameters are mostly needed for adjusting the plot appearance.
x_with_imputations

Numeric Vector or Time Series (ts) object with NAs replaced by imputed values. This parameter and x_with_imputation shave to be set.The rest of the parameters are mostly needed for adjusting the plot appearance.
x_with_truth

Numeric Vector or Time Series (ts) object with the real values (optional parameter). If the ground truth is known (e.g. in experiments where the missing values were artificially added) it can be displayed in the plot with this parameter. Default is NULL (ground truth not known).
x_axis_labels

For adding specific x-axis labels. Takes a vector of Date or POSIXct objects as an input (needs the same length as x_with_na). The Default (NULL) uses the observation numbers as x-axis tick labels.
title

Title of the Plot.
subtitle

Subtitle of the Plot.
xlab

Label for x-Axis.
ylab

Label for y-Axis.
color_points

Color for the Symbols/Points of the non-NA Observations.
color_imputations

Color for the Symbols/Points of the Imputed Values.
color_truth

Color for the Symbols/Points of the NA value Ground Truth (only relevant when x_with_truth available).
color_lines

Color for the Lines connecting the Observations/Points.
shape_points

Shape for the Symbols/Points of the non-NA observations. See https://ggplot2.tidyverse.org/articles/ggplot2-specs.html as reference.
shape_imputations

Shape for the Symbols/Points of the imputed values. See https://ggplot2.tidyverse.org/articles/ggplot2-specs.html as reference.
shape_truth

Shape for the Symbols/Points of the NA value Ground Truth (only relevant when x_with_truth available).
size_points

Size for the Symbols/Points of the non-NA Observations.
size_imputations

Size for the Symbols/Points of the Imputed Values.
size_truth

Size for the Symbols/Points of the NA value Ground Truth (only relevant when x_with_truth available).
size_lines

Size for the Lines connecting the Observations/Points.
linetype

Linetype for the Lines connecting the Observations/Points.
connect_na

If TRUE the Imputations are connected to the non-NA observations in the plot. Otherwise there are no connecting lines between symbols in NA areas.
legend

If TRUE a Legend is added at the bottom.
legend_size

Size of the Symbols used in the Legend.
label_known

Legend label for the non-NA Observations.
label_imputations

Legend label for the Imputed Values.
label_truth

Legend label for the Ground Truth of the NA values.
theme

Set a Theme for ggplot2. Default is ggplot2::theme_linedraw(). (theme_linedraw)

Details

This plot can be used, to visualize imputed values for a time series. Imputed values (filled NA gaps) are shown in a different color than the other values. If real values (ground truth) for the NA gaps are known, they can be optionally added in a different color.

The only really needed parameters for this function are x_with_na (the time series with NAs before imputation) and x_with_imputations (the time series without NAs after imputation). All other parameters are msotly for altering the appearance of the plot.

As long as the input is univariate and numeric the function also takes data.frame, tibble, tsibble, zoo, xts as an input.

The plot can be adjusted to your needs via the function parameters. Additionally, for more complex adjustments, the output can also be adjusted via ggplot2 syntax. This is possible, since the output of the function is a ggplot2 object. Also take a look at the Examples to see how adjustments are made.

See also

ggplot_na_distribution, ggplot_na_distribution2, ggplot_na_gapsize

Author

Steffen Moritz, Sebastian Gatscha

Examples

# Example 1: Visualize imputation by na_mean
imp_mean <- na_mean(tsAirgap)
ggplot_na_imputations(tsAirgap, imp_mean)



# Example 2: Visualize imputation by na_locf and added ground truth 
imp_locf <- na_locf(tsAirgap)
ggplot_na_imputations(x_with_na = tsAirgap, 
                      x_with_imputations = imp_locf,
                      x_with_truth = tsAirgapComplete
                      )

#> Error in ggplot_na_imputations(x_with_na = tsAirgap, x_with_imputations = imp_locf,     x_with_truth = tsAirgapComplete): object 'imp_locf' not found


# Example 3: Visualize imputation by na_kalman
imp_kalman <- na_kalman(tsAirgap)
ggplot_na_imputations(x_with_na = tsAirgap, x_with_imputations = imp_kalman)



# Example 4: Same as example 1, just written with pipe operator
tsAirgap %>%
  na_mean() %>%
  ggplot_na_imputations(x_with_na = tsAirgap)

  

# Example 5: Visualize imputation by na_seadec - different color for imputed points
# Plot adjustments via ggplot_na_imputations function parameters
imp_seadec <- na_seadec(tsAirgap)
ggplot_na_imputations(x_with_na = tsAirgap, 
                      x_with_imputations = imp_seadec,
                      color_imputations = "gold")



# Example 6: Visualize imputation - different theme, point size imputations
# Plot adjustments via ggplot_na_imputations function parameters
imp_seadec <- na_seadec(tsAirgap)
ggplot_na_imputations(x_with_na = tsAirgap, 
                      x_with_imputations = imp_seadec,
                      theme = ggplot2::theme_classic(),
                      size_imputations = 5)


                 
# Example 7: Visualize imputation - title, subtitle in center
# Plot adjustments via ggplot2 syntax
imp_seadec <- na_seadec(tsAirgap)
ggplot_na_imputations(x_with_na = tsAirgap,  x_with_imputations = imp_seadec) + 
    ggplot2::theme(plot.title = ggplot2::element_text(hjust = 0.5)) +
    ggplot2::theme(plot.subtitle = ggplot2::element_text(hjust = 0.5))   



# Example 8: Visualize imputation - title in center, no subtitle
# Plot adjustments via ggplot2 syntax and function parameters
imp_mean <- na_mean(tsAirgap)
ggplot_na_imputations(x_with_na = tsAirgap,  
                      x_with_imputations = imp_mean,
                      subtitle = NULL) +
     ggplot2::theme(plot.title = ggplot2::element_text(hjust = 0.5))