Description Usage Arguments Details Value See Also Examples

The `"assign"`

attribute on model matrices describes which columns
come from which terms in the model formula. It has two versions. R uses
the original version, but the alternate version found in
S-plus is sometimes useful.

1 2 3 4 | ```
## Default S3 method:
attrassign(object, tt,...)
## S3 method for class 'lm'
attrassign(object,...)
``` |

`object` |
model matrix or linear model object |

`tt` |
terms object |

`...` |
ignored |

For instance consider the following

1 2 |

R gives the compact for for assign, a vector (0, 1, 2, 3, 3, 3); which can be read as “the first column of the X matrix (intercept) goes with none of the terms, the second column of X goes with term 1 of the model equation, the third column of X with term 2, and columns 4-6 with term 3”.

The alternate (S-Plus default) form is a list

1 2 3 4 5 | ```
$(Intercept) 1
$age 2
$sex 3
$factor(ph.ecog) 4 5 6
``` |

A list with names corresponding to the term names and elements that are vectors indicating which columns come from which terms

1 2 3 4 5 6 7 8 9 10 | ```
formula <- Surv(time,status)~factor(ph.ecog)
tt <- terms(formula)
mf <- model.frame(tt,data=lung)
mm <- model.matrix(tt,mf)
## a few rows of data
mm[1:3,]
## old-style assign attribute
attr(mm,"assign")
## alternate style assign attribute
attrassign(mm,tt)
``` |

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