Graphical and tabular effect displays, e.g., of interactions, for linear (including fit via gls), multivariate-linear, generalized linear, multinomial-logit, proportional-odds logit, mixed-effect, polytomous latent-class, and some other models; (multidimensional) component+residual plots for linear and generalized linear models.
effect
(Package: effects) :
Functions For Constructing Effect Plots
effect and Effect construct an "eff" object for a term (usually a high-order term) in a linear (fit by lm or gls) or generalized linear model (fit by glm), or an "effpoly" object for a term in a multinomial or proportional-odds logit model (fit respectively by multinom or polr), absorbing the lower-order terms marginal to the term in question, and averaging over other terms in the model. For multivariate linear models (mlm), the function constructs a list of "eff" objects separately for the various response variables.
providing 
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