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Bend or Straighten Selected edges

Source: R/set_curve.R
set_curve.Rd

Set the curve attributes of selected edges.

Usage

set_curve(
  semPaths_plot,
  curve_list = NULL,
  how = c("value", "ratio"),
  check_direction = TRUE
)

Arguments

semPaths_plot

A qgraph::qgraph object generated by semPlot::semPaths, or a similar qgraph object modified by other semptools functions. It can also be a list of qgraph::qgraph objects, probably though not necessarily from a multigroup model. If it is a list of qgraph::qgraph objects, then the function will be applied to all the objects.

curve_list

A named vector or a list of named list. For a named vector, the name of an element should be the path as specified by lavaan::model.syntax or as appeared in lavaan::parameterEstimates(). For example, to change the curve attribute of the path regressing y on x, the name should be "y ~ x". To change the curve attribute of the covariance between x1 and x2, the name should be "x1 ~~ x2". For example, c("y ~ x1" = -3, "x1 ~~ x2" = 2) change the curve attributes of the path from x1 to y and the covariance between x1 and x2 to -3 and 2, respectively. The order of the two nodes may matter for covariances. Therefore, if the curve of a covariance is not changed, try switching the order of the two nodes. For a list of named lists, each named list should have three named values: from, to, and new_curve. The curve attribute of the edge from from to to will be set to new_curve.

how

How the width will be changed. If "ratio", then the new width is the original width multiplied by the supplied value. If "value", then the new width is set to the supplied value.

check_direction

If FALSE, the direction of an edge is ignored. For example, both y ~ x and x ~ y will affect y ~ x, x ~ y, and y ~~ x. Useful when we want to change an edge regardless of its direction and whether it is directional.

Value

A qgraph::qgraph based on the original one, with curve attributes for selected edges changed. If semPaths_plot is a list of qgraph::qgraph objects, then a list of processed qgraph::qgraph objects will be returned.

Details

Modified a qgraph::qgraph object generated by semPlot::semPaths and change the curve attributes of selected edges.

If how is set to "ratio", then the new curve value is equal to the old curve value multiplied by the supplied value. This mode lets users increase or decrease the curvature of a curve without knowing the original value.

Examples

mod_pa <-
 'x1 ~~ x2
  x3 ~  x1 + x2
  x4 ~  x1 + x3
 '
fit_pa <- lavaan::sem(mod_pa, pa_example)
lavaan::parameterEstimates(fit_pa)[, c("lhs", "op", "rhs", "est", "pvalue")]
#>   lhs op rhs   est pvalue
#> 1  x1 ~~  x2 0.005  0.957
#> 2  x3  ~  x1 0.537  0.000
#> 3  x3  ~  x2 0.376  0.000
#> 4  x4  ~  x1 0.111  0.382
#> 5  x4  ~  x3 0.629  0.000
#> 6  x3 ~~  x3 0.874  0.000
#> 7  x4 ~~  x4 1.194  0.000
#> 8  x1 ~~  x1 0.933  0.000
#> 9  x2 ~~  x2 1.017  0.000
m <- matrix(c("x1",   NA,   NA,
               NA, "x3", "x4",
             "x2",   NA,   NA), byrow = TRUE, 3, 3)
p_pa <- semPlot::semPaths(fit_pa, whatLabels="est",
           style = "ram",
           nCharNodes = 0, nCharEdges = 0,
           layout = m)


my_curve_vector <- c("x2 ~~ x1" = -1,
                    "x4 ~ x1" = 1)

p_pa2v <- set_curve(p_pa, my_curve_vector)
plot(p_pa2v)


my_curve_list <- list(list(from = "x1", to = "x2", new_curve = -1),
                    list(from = "x1", to = "x4", new_curve =  1))

p_pa2l <- set_curve(p_pa, my_curve_list)
plot(p_pa2l)