PyROOT: Finding local minima/maxima in a TGraph

iMi · May 22, 2020, 2:45pm

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ROOT Version: ROOT 6.18/04
Platform: Debian GNU/Linux 10 (buster)
Compiler: /interpreter Python 3.6.9 [GCC 7.3.0] on linux

Hello,

I am aiming at finding the coordinates of the local minima and maxima of a TGraph.

Found this post :

How can I translate the answer by @moneta into PyROOT?

Thanks for looking into it!

etejedor · May 26, 2020, 8:28am

Hi,

This should work (note the graph is just a dummy):

import ROOT

xmin = 0
xmax = 10

graph = ROOT.TGraph()

def myfun(x, p):
    return graph.Eval(x[0])

f = ROOT.TF1("f", myfun, xmin, xmax, 0)

Here you can find more examples of using Python callables to construct TFX objects:

github.com

root-project/root/blob/master/bindings/pyroot_experimental/pythonizations/test/tf_pycallables.py

"""
Tests for passing Python callables when constructing TFX classes.

This feature is not implemented by a PyROOT pythonization, but by a converter of
Cppyy that creates a C++ wrapper to invoke the Python callable.
"""

import unittest
import math

import ROOT


def pyf_tf1_identity(x, p):
    return x[0]


def pyf_tf1_params(x, p):
    return p[0] * x[0] + p[1]

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system · June 9, 2020, 8:28am

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