note that a histogram is much more than just points on a 2D plane.
it carries a bunch of statistical informations.
one can use root-dump to print – in ASCII art – the content of histograms (1D and 2D):
$> root-ls gauss-h1.root
=== [gauss-h1.root] ===
version: 60806
TH1D h1d h1d (cycle=1)
TH1F h1f h1f (cycle=1)
TH1F h1d-var h1d-var (cycle=1)
TH1F h1f-var h1f-var (cycle=1)
$> root-dump -name=h1d-var gauss-h1.root
>>> file[gauss-h1.root]
key[000]: h1d;1 "h1d" (TH1D)
key[001]: h1f;1 "h1f" (TH1F)
key[002]: h1d-var;1 "h1d-var" (TH1F)
BEGIN YODA_HISTO1D /h1d-var
Path=/h1d-var
Title=h1d-var
Type=Histo1D
# Mean: 2.812016e-02
# Area: 1.100600e+04
# ID ID sumw sumw2 sumwx sumwx2 numEntries
Total Total 1.100600e+04 1.211000e+04 3.094905e+02 7.128989e+04 10004
Underflow Underflow 2.000000e+00 2.000000e+00 0.000000e+00 0.000000e+00 2
Overflow Overflow 4.000000e+00 8.000000e+00 0.000000e+00 0.000000e+00 2
# xlow xhigh sumw sumw2 sumwx sumwx2 numEntries
-4.000000e+00 -3.200000e+00 6.600000e+00 7.260000e+00 0.000000e+00 0.000000e+00 6
-3.200000e+00 -2.400000e+00 7.259995e+01 7.986000e+01 0.000000e+00 0.000000e+00 66
-2.400000e+00 -1.600000e+00 5.434013e+02 5.977400e+02 0.000000e+00 0.000000e+00 494
-1.600000e+00 -8.000000e-01 1.708276e+03 1.879130e+03 0.000000e+00 0.000000e+00 1553
-8.000000e-01 0.000000e+00 3.130664e+03 3.443660e+03 0.000000e+00 0.000000e+00 2846
0.000000e+00 8.000000e-01 3.136165e+03 3.449710e+03 0.000000e+00 0.000000e+00 2851
8.000000e-01 1.600000e+00 1.753375e+03 1.928740e+03 0.000000e+00 0.000000e+00 1594
1.600000e+00 2.400000e+00 5.401014e+02 5.941100e+02 0.000000e+00 0.000000e+00 491
2.400000e+00 3.200000e+00 1.011999e+02 1.113200e+02 0.000000e+00 0.000000e+00 92
3.200000e+00 4.000000e+00 7.700000e+00 8.470000e+00 0.000000e+00 0.000000e+00 7
END YODA_HISTO1D
key[003]: h1f-var;1 "h1f-var" (TH1F)
root-dump converts TH{1,2}x histograms to YODA histograms.
That said, it seems you want to extract that data to plot it with another plotting system.
Which one is it? There is perhaps a less convoluted way to do that…
hth,
-s