Add a way to keep track of dataframe actions

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Hi,

I have something like:

import ROOT

df = ROOT.RDataFrame(10000)

df = df.Define("B_PT", "gRandom->Uniform(0, 2000)")
df = df.Define("mass", "gRandom->Uniform(0, 5000)")

df = df.Filter("B_PT > 1000")
df = df.Define("pass_mass", "mass < 3000")

df = df.Range(1000)

Here there are actions, definitions, filters etc. How are we supposed to keep track of what happened to that dataframe? I only see Report but besides giving me a cutflow, it does not show me what was defined or how. This makes working with dataframes completely obscure, we get data from a dataframe, but where did that dataframe came from? Did any filter that was not supposed to happen was used? Was a column defined incorrectly? There is no way to know.

The only way I see to fix this problem properly is to wrap these dataframes into a class that keeps track of the actions, exposes Range, Filter etc and implements a save_actions(path, as_json = True). But wouldn't it make more sense if that method exists upstream in ROOT itself?

Cheers.

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@acampove

Hi @acampove ,

What you ask for already exists and is documented https://root.cern/doc/v632/classROOT_1_1RDataFrame.html#representgraph .

Hi @acampove ,

What you ask for already exists and is documented https://root.cern/doc/v632/classROOT_1_1RDataFrame.html#representgraph .

That does not do what I asked. How will that graph show me the definition if I do:

import ROOT

df = ROOT.RDataFrame(10000)

df = df.Define("B_PT", "gRandom->Uniform(0, 2000)")
df = df.Define("mass", "gRandom->Uniform(0, 5000)")

df = df.Filter("B_PT > 1000", "B_PT selection")
df = df.Define("pass_mass", "mass < 3000")

df = df.Filter("pass_mass", "Mass selection")
df = df.Range(1000)

graph = ROOT.RDF.SaveGraph(df)
print(graph)

with open("graph.dot", "w") as f:
    f.write(graph)

I see:

digraph {
        6 [label="Range", style="filled", fillcolor="#9574b4", shape="diamond"];
        4 [label="Mass selection", style="filled", fillcolor="#0f9d58", shape="hexagon"];
        5 [label="Define\npass_mass", style="filled", fillcolor="#4285f4", shape="ellipse"];
        1 [label="B_PT selection", style="filled", fillcolor="#0f9d58", shape="hexagon"];
        2 [label="Define\nmass", style="filled", fillcolor="#4285f4", shape="ellipse"];
        3 [label="Define\nB_PT", style="filled", fillcolor="#4285f4", shape="ellipse"];
        0 [label="Empty source\nEntries: 10000", style="filled", fillcolor="#f4b400", shape="ellipse"];
        4 -> 6;
        5 -> 4;
        1 -> 5;
        2 -> 1;
        3 -> 2;
        0 -> 3;
}

How do I know the definitions or what filter was applied? I am using range with 1000,but I do not see that 1000 anywhere. I believe the Redefine would not be tracked either.

Ok then IIUC what you are asking is a text form that precisely represents what the computation graph you defined is going to apply on your data, including the expressions of filters, how many entries you select with a Range, the expression of a Redefine. To me, this sounds like you want to see what your code does, but isn't the code itself already telling you that? I do not understand what's missing here.

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Add a way to keep track of dataframe actions #24057

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Add a way to keep track of dataframe actions #24057

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vepadulano commented on Nov 9, 2026

acampove commented on Nov 9, 2026

vepadulano commented on Nov 9, 2026

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