## \file
## \ingroup tutorial_graphs
## \notebook -js
## This macro illustrates the use of the time axis on a TGraph
## with data read from a text file containing the SWAN usage
## statistics during July 2017.
##
## \macro_image
## \macro_code
##
## \authors Danilo Piparo, Olivier Couet

import ROOT

# Open the data file. This csv contains the usage statistics of a CERN IT
# service, SWAN, during two weeks. We would like to plot this data with
# ROOT to draw some conclusions from it.
dirName = str(ROOT.gROOT.GetTutorialDir())
dirName += "/graphs/"
dirName= dirName.replace("/./", "/")
inputFileName = "%s/SWAN2017.dat" %dirName

# Create the time graph
g = ROOT.TGraph()
g.SetTitle("SWAN Users during July 2017;Time;Number of Sessions")

# Read the data and fill the graph with time along the X axis and number
# of users along the Y axis

lines = open(inputFileName, "r").readlines()

for i, line in enumerate(lines):
    d, h, value = line.split()
    g.SetPoint(i, ROOT.TDatime("%s %s" %(d,h)).Convert(), float(value))

# Draw the graph
c = ROOT.TCanvas("c", "c", 950, 500)
c.SetLeftMargin(0.07)
c.SetRightMargin(0.04)
c.SetGrid()
g.SetLineWidth(3)
g.SetLineColor(ROOT.kBlue)
g.Draw("al")
g.GetYaxis().CenterTitle()

# Make the X axis labelled with time
xaxis = g.GetXaxis()
xaxis.SetTimeDisplay(1)
xaxis.CenterTitle()
xaxis.SetTimeFormat("%a %d")
xaxis.SetTimeOffset(0)
xaxis.SetNdivisions(-219)
xaxis.SetLimits(ROOT.TDatime(2017, 7, 3, 0, 0, 0).Convert(), ROOT.TDatime(2017, 7, 22, 0, 0, 0).Convert())
xaxis.SetLabelSize(0.025)
xaxis.CenterLabels()