# Create path diagrams to visualise model specifications

    library(lcsm)

### Plot simplified path diagrams of LCSMs

This function is work in progress and can only plot univariate and bivariate LCSMs that were specified with `fit_uni_lcsm()` or `fit_bi_lcsm()`. Modified LCSMs will probably return errors as the layout matrix that gets created by this plot function only supports the specifications that can be modelled with this package. The input arguments for plotting a simplified path dioagram are:

- the estimated lavaan object `lavaan_object`,
- the `lavaan_syntax` and ,
- `lcsm` indicating whether the LCSM is “univariate” or “bivariate”

Optional arguments can be used to change the look of the plot, for example:

- `lcsm_colours` can be used to highlight the different parts of the latent change score model
  - white: observed scores
  - green: latent true scores
  - blue: latent change scores
  - yellow: latent change scores

Further arguments can be passed on to `semPlot::semPaths()`, for example:

- `what`, “path” to show unweighted gray edges, “par” to show parameter estimates as weighted (green/red) edges
- `whatLabels`, “label” to show edege names as label or “est” for parameter estimates, “hide” to hide edge labels

#### Univariate LCSM

    # Fit bivariate lcsm and save the results
    uni_lavaan_results <- fit_uni_lcsm(data = data_uni_lcsm,
                                       var = c("x1", "x2", "x3", "x4", "x5"),
                                       model = list(alpha_constant = TRUE,
                                                    beta = FALSE,
                                                    phi = TRUE)
                                      )
    #> Warning: lavaan->lav_data_full():
    #>    some cases are empty and will be ignored: 239.

    # Save the lavaan syntax that is used to create the layout matrix for semPlot
    uni_lavaan_syntax <- fit_uni_lcsm(data = data_uni_lcsm,
                                      var = c("x1", "x2", "x3", "x4", "x5"),
                                      model = list(alpha_constant = TRUE,
                                                   beta = FALSE,
                                                   phi = TRUE),
                                      return_lavaan_syntax = TRUE)

    # Plot the results
    plot_lcsm(lavaan_object = uni_lavaan_results,
              lavaan_syntax = uni_lavaan_syntax,
              edge.label.cex = .9,
              lcsm_colours = TRUE,
              lcsm = "univariate")

#### Bivariate LCSM

    # Fit bivariate lcsm and save the results
    bi_lavaan_results <- fit_bi_lcsm(data = data_bi_lcsm,
                                     var_x = c("x1", "x2", "x3", "x4", "x5"),
                                     var_y = c("y1", "y2", "y3", "y4", "y5"),
                                     model_x = list(alpha_constant = TRUE,
                                                    beta = TRUE,
                                                    phi = FALSE),
                                     model_y = list(alpha_constant = TRUE,
                                                    beta = TRUE,
                                                    phi = TRUE),
                                     coupling = list(delta_lag_xy = TRUE,
                                                     xi_lag_yx = TRUE))

    # Save the lavaan syntax that is used to create the layout matrix for semPlot
    bi_lavaan_syntax <- fit_bi_lcsm(data = data_bi_lcsm,
                                    var_x = c("x1", "x2", "x3", "x4", "x5"),
                                    var_y = c("y1", "y2", "y3", "y4", "y5"),
                                    model_x = list(alpha_constant = TRUE,
                                                   beta = TRUE,
                                                   phi = FALSE),
                                    model_y = list(alpha_constant = TRUE,
                                                   beta = TRUE,
                                                   phi = TRUE),
                                    coupling = list(delta_lag_xy = TRUE,
                                                    xi_lag_yx = TRUE),
                                    return_lavaan_syntax = TRUE)

    # Plot the results
    plot_lcsm(lavaan_object = bi_lavaan_results,
              lavaan_syntax = bi_lavaan_syntax,
              lcsm_colours = TRUE,
              whatLabels = "hide",
              lcsm = "bivariate")