fid {glmnet} | R Documentation |

## Helper function for Cox deviance and gradient

### Description

Helps to find ties in death times of data.

### Usage

```
fid(x, index)
```

### Arguments

`x` |
Sorted vector of death times. |

`index` |
Vector of indices for the death times. |

### Value

A list with two arguments.

`index_first` |
A vector of indices for the first observation at each death time as they appear in the sorted list. |

`index_ties` |
If there are no ties at all, this is NULL. If not, this is a list with length equal to the number of unique times with ties. For each time with ties, index_ties gives the indices of the observations with a death at that time. |

### Examples

```
# Example with no ties
glmnet:::fid(c(1, 4, 5, 6), 1:5)
# Example with ties
glmnet:::fid(c(1, 1, 1, 2, 3, 3, 4, 4, 4), 1:9)
```

[Package

*glmnet*version 4.1-8 Index]