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Find peaks in a spectrum

Source: R/spct.peaks.r
find_peaks.Rd

This function finds all peaks (local maxima) in a spectrum, using a user provided size threshold relative to the tallest peak (global maximum) bellow which found peaks are ignored—i.e., not included in the returned value. This is a wrapper built on top of function peaks() from package 'splus2R'.

Usage

find_peaks(x, ignore_threshold = 0, span = 3, strict = TRUE, na.rm = FALSE)

Arguments

x

numeric vector

ignore_threshold

numeric Value between 0.0 and 1.0 indicating the relative size compared to tallest peak threshold below which peaks will be ignored. Negative values set a threshold so that the tallest peaks are ignored, instead of the shortest.

span

integer A peak is defined as an element in a sequence which is greater than all other elements within a window of width span centered at that element. Use NULL for the global peak.

strict

logical If TRUE, an element must be strictly greater than all other values in its window to be considered a peak.

na.rm

logical indicating whether NA values should be stripped before searching for peaks.

Value

A logical vector of the same length as x. Values that are TRUE correspond to local peaks in the data.

Note

This function is a wrapper built on function peaks from splus2R and handles non-finite (including NA) values differently than splus2R::peaks, instead of giving an error they are replaced with the smallest finite value in x.

See also

peaks

Other peaks and valleys functions: find_spikes(), get_peaks(), peaks(), replace_bad_pixs(), spikes(), valleys(), wls_at_target()

Examples

with(sun.data, w.length[find_peaks(s.e.irrad)])
#>   [1] 315 317 321 327 330 332 335 340 343 345 347 350 354 360 364 366 370 378
#>  [19] 381 385 387 391 395 402 404 409 412 414 416 419 421 426 433 436 442 444
#>  [37] 448 451 457 461 464 466 468 472 475 478 480 482 488 490 493 495 499 503
#>  [55] 506 509 512 516 518 522 525 529 531 536 538 545 547 550 552 555 558 561
#>  [73] 563 565 568 570 573 577 582 587 591 594 597 600 605 608 612 615 619 621
#>  [91] 627 629 633 635 638 642 651 653 662 668 674 688 692 697 704 709 712 722
#> [109] 727 730 734 741 744 747 751 754 762 771 774 777 779 782 785 792 794 798