Using Histogram · FHist.jl

Basic attributes

binedges: Get the bin edges of the histogram, for 1D histogram, it returns just a vector. For others, it returns a tuple of vectors. If you need a tuple of vectors, use h.binedges at your own risk.
bincounts: Get the bin counts (weights) of the histogram.
sumw2: Get the sum of weights squared of the histogram, it has the same shape as bincounts(h).
nentries: Get the number of times a histogram is filled (push!ed)

Derived attributes

bincenters: Get the bin centers of the histogram, for 1D histogram, it returns just a vector. For others, it returns a tuple of vectors.
binerrors: Get the error of each bin of the histogram. By default it calls sqrt() on each entry of sumw2 as an approximation.
mean, std, median, quantile, weighted by histogram bincounts().

FHist.integral — Function

integral(h; width=false)

Get the integral a histogram; width means multiply each bincount by their bin width when calculating the integral.

Warning

width keyword argument only works with 1D histogram at the moment.

Warning

Be aware of the approximation you make when using width=true with histogram with overflow bins, the overflow bins (i.e. the left/right most bins) width will be taken "as is".

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Manipulating histogram

This section includes adding data to histogram, and other operations that return a histogram (may with reduced dimensionality)

FHist.atomic_push! — Function

push!(h::Hist1D, val::Real, wgt::Real=1)
atomic_push!(h::Hist1D, val::Real, wgt::Real=1)

Adding one value at a time into histogram. sumw2 (sum of weights^2) accumulates wgt^2 with a default weight of 1. atomic_push! is a slower version of push! that is thread-safe.

N.B. To append multiple values at once, use broadcasting via push!.(h, [-3.0, -2.9, -2.8]) or push!.(h, [-3.0, -2.9, -2.8], 2.0)

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push!(h::Hist2D, valx::Real, valy::Real, wgt::Real=1)
atomic_push!(h::Hist2D, valx::Real, valy::Real, wgt::Real=1)

Adding one value at a time into histogram. sumw2 (sum of weights^2) accumulates wgt^2 with a default weight of 1. atomic_push! is a slower version of push! that is thread-safe.

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push!(h::Hist3D, valx::Real, valy::Real, wgt::Real=1)
atomic_push!(h::Hist3D, valx::Real, valy::Real, wgt::Real=1)

Adding one value at a time into histogram. sumw2 (sum of weights^2) accumulates wgt^2 with a default weight of 1. atomic_push! is a slower version of push! that is thread-safe.

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FHist.cumulative — Function

cumulative(h::Hist1D; forward=true)

Create a cumulative histogram. If forward, start summing from the left.

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FHist.rebin — Function

rebin(h::Hist1D, n::Int=1)
rebin(h::Hist1D, edges::AbstractVector{<:Real})
rebin(n::Int)
rebin(edges::AbstractVector{<:Real})

Rebin a histogram by merging existing bins. When provided an integer n, the function merges n consecutive bins and returns nbins(h) / n bins. When provided a collection of bin edges edges, the function returns a new histogram whose bin edges match edges; every element of edges must align with the original bin edges and span the full histogram range.

If the edges is an array and doesn't include original histogram's leftmost and rightmost edges, those bins will be ignored.

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rebin(h::Hist2D, nx::Int=1, ny::Int=nx)
rebin(nx::Int, ny::Int) = h::Hist2D -> rebin(h, nx, ny)

Merges nx (ny) consecutive bins into one along the x (y) axis by summing.

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FHist.restrict — Function

restrict(h::Hist1D, low=-Inf, high=Inf)
restrict(low=-Inf, high=Inf) = h::Hist1D -> restrict(h, low, high)

Returns a new histogram with a restricted x-axis. restrict(h, 0, 3) (or h |> restrict(0, 3)) will return a slice of h where the bin centers are in [0, 3] (inclusive).

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restrict(h::Hist2D, xlow=-Inf, xhigh=Inf, ylow=-Inf, yhigh=Inf)
restrict(xlow=-Inf, xhigh=Inf, ylow=-Inf, yhigh=Inf) = h::Hist2D -> restrict(h, xlow, xhigh, ylow, yhigh)

Returns a new histogram with a restricted x-axis. restrict(h, 0, 3) (or h |> restrict(0, 3)) will return a slice of h where the bin centers are in [0, 3] (inclusive).

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FHist.profile — Function

profile(h::Hist2D, axis::Symbol=:x)
profile(axis::Symbol=:x) = h::Hist2D -> profile(h, axis)

Returns the axis-profile of the 2D histogram by calculating the weighted mean over the other axis. profile(h, :x) will return a Hist1D with the y-axis edges of h.

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FHist.project — Function

project(h::Hist2D, axis::Symbol=:x)
project(axis::Symbol=:x) = h::Hist2D -> project(h, axis)

Computes the :x (:y) axis projection of the 2D histogram by summing over the y (x) axis. Returns a Hist1D.

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project(h::Hist3D, axis::Symbol=:x)
project(axis::Symbol=:x) = h::Hist3D -> project(h, axis)

Computes the :x/:y/:z axis projection of the 3D histogram by summing over the specified axis. Returns a Hist2D.

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