add --field-prefix via click.option and update doc

.github/workflows/pythontests.yml

@@ -40,6 +40,7 @@ jobs:
         wget --quiet http://scikit-hep.org/uproot3/examples/Event.root
         histoprint -s Event.root -f T/event/fTracks/fTracks.fYfirst -f T/event/fTracks/fTracks.fYlast[:,0]
         histoprint -s Event.root -f T/fTracks.fYfirst -f T/event/fTracks/fTracks.fYlast[:,0] -C 'fNtrack > 5'
+        histoprint -s Event.root --field-prefix T/event/fTracks/fTracks. -f fYfirst -f fYlast[:,0]
         histoprint -s Event.root -f htime
 
   pre-commit:

README.rst

@@ -179,6 +179,12 @@ It can read in files or take data directly from STDIN::
                                       'tree/branch[:,2]' to histogram the 3rd
                                       elements of a vector-like branch.
 
+      --field-prefix TEXT             String to prepend to each argument passed to
+                                      --field option following --field-prefix E.g.
+                                      'histoprint -f Muon_eta --field-prefix Tau_
+                                      -f eta -f phi' ... would refer to fields
+                                      'Muon_eta', 'Tau_eta' and 'Tau_phi''
+
       -C, --cut TEXT                  Filter the data to be plotted by a cut
                                       condition. For ROOT files, variables must be
                                       referenced by their branch name within the

histoprint/cli.py

@@ -10,6 +10,12 @@
 import histoprint.formatter as formatter
 
 
+def fieldprefixer_callback(ctx, param, fields):
+    if "field_prefix" in ctx.params:
+        fields = map(lambda field: ctx.params["field_prefix"] + field, fields)
+    return tuple(fields)
+
+
 @click.command()
 @click.argument("infile", type=click.Path(exists=True, dir_okay=False, allow_dash=True))
 @click.option(
@@ -74,6 +80,15 @@
     "single TH1, or one or more paths to TTree branches. Also supports slicing "
     "of array-like branches, e.g. use 'tree/branch[:,2]' to histogram the 3rd "
     "elements of a vector-like branch.",
+    callback=fieldprefixer_callback,
+)
+@click.option(
+    "--field-prefix",
+    "field_prefix",
+    type=str,
+    multiple=False,
+    help="String to prepend to all values indicated with --field option, "
+    "ignores position where this and --field options are specified.",
 )
 @click.option(
     "-C",
@@ -109,6 +124,7 @@ def histoprint(infile, **kwargs):
 
     INFILE can be '-', in which case the data is read from STDIN.
     """
+    del kwargs["field_prefix"]
 
     # Read file into buffer for use by implementations
     try:

tests/test_basic.py

@@ -3,7 +3,9 @@
 import numpy as np
 import pytest
 from uhi.numpy_plottable import ensure_plottable_histogram
+from click.testing import CliRunner
 
+from histoprint.cli import histoprint as cli
 import histoprint as hp
 
 
@@ -181,3 +183,40 @@ def test_rich_histogram():
     tab.add_row(hist, Align.center(hist), Align.right(hist))
 
     rich.print(tab)
+
+
+def test_cli_opt_field_prefix():
+    """Test equivalence of --field-prefix cli option to explicit prepend on --field."""
+
+    runner = CliRunner()
+
+    # tests for fields "two" and "three" since share prefix of "t"
+    res = runner.invoke(
+        cli,
+        [
+            "-s",
+            "tests/data/histograms.root",
+            "-f",
+            "two",
+            "-f",
+            "three",
+        ],
+    )
+    res_prefixed = runner.invoke(
+        cli,
+        [
+            "-s",
+            "tests/data/histograms.root",
+            "-f",
+            "wo",
+            "-f",
+            "hree",
+            "--field-prefix",
+            "t",
+        ],
+    )
+
+    # assert succesful equivalent output
+    assert res.exit_code == 0
+    assert res_prefixed.exit_code == 0
+    assert res.output == res_prefixed.output