# Projected Slingshot

ti_projected_slingshot(shrink = 1L, reweight = TRUE, reassign = TRUE,
thresh = 0.001, maxit = 10L, stretch = 2,
smoother = "smooth.spline", shrink.method = "cosine")

## Arguments

shrink |
Logical or numeric between 0 and 1, determines whether and how
much to shrink branching lineages toward their average prior to the split.
Domain: e^U(-Inf, 0.00). Default: 1. Format: numeric. |

reweight |
Logical, whether to allow cells shared between lineages to be
reweighted during curve-fitting. If `TRUE` , cells shared between lineages will
be weighted by: distance to nearest curve / distance to curve. Default: TRUE.
Format: logical. |

reassign |
Logical, whether to reassign cells to lineages at each
iteration. If TRUE, cells will be added to a lineage when their projection
distance to the curve is less than the median distance for all cells currently
assigned to the lineage. Additionally, shared cells will be removed from a
lineage if their projection distance to the curve is above the 90th percentile
and their weight along the curve is less than 0.1. Default: TRUE. Format:
logical. |

thresh |
Numeric, determines the convergence criterion. Percent change in
the total distance from cells to their projections along curves must be less
than thresh. Default is 0.001, similar to principal.curve. Domain: e^U(-11.51,
11.51). Default: 0.001. Format: numeric. |

maxit |
Numeric, maximum number of iterations, see principal.curve.
Domain: U(0, 50). Default: 10. Format: integer. |

stretch |
Numeric factor by which curves can be extrapolated beyond
endpoints. Default is 2, see principal.curve. Domain: e^U(-Inf, 1.61). Default:
2. Format: numeric. |

smoother |
Choice of scatter plot smoother. Same as principal.curve, but
"lowess" option is replaced with "loess" for additional flexibility. Domain:
smooth.spline, loess, periodic.lowess. Default: smooth.spline. Format:
character. |

shrink.method |
Character denoting how to determine the appropriate amount
of shrinkage for a branching lineage. Accepted values are the same as for
`kernel` in `density()` (default is `"cosine"` ), as well as `"tricube"` and
`"density"` . See 'Details' for more. Domain: cosine, tricube, density.
Default: cosine. Format: character. |

## Value

A TI method wrapper to be used together with
`infer_trajectory`

## References

Street, K., Risso, D., Fletcher, R.B., Das, D., Ngai, J., Yosef,
N., Purdom, E., Dudoit, S., 2018. Slingshot: cell lineage and pseudotime
inference for single-cell transcriptomics. BMC Genomics 19.