Refer to columns that have dot in their names

[cool-RR]

I'd like to use addcol-expr, but the columns I want to refer to have a dot in their name v.a0. This confuses visidata, probably because it's not a legal Python variable name. I know I can temporarily rename the column, but is there a better solution?

[midichef]

As an experiment, I drafted some expression code for .visidatarc that lets you refer to a column called v.a0 by using v_a0. It translates any column name characters in '.,<>()[]+-/% ' to underscores (including spaces). So in an expression, you can refer to a column a[0] using a_0_ or a column w - margin as w___margin.

I think it's only suitable for advanced users to experiment with, however. One thing to remember if you try it: any future changes to evalExpr() in sheets.py would need to be worked back into this code in your .visidatarc.

## modification to refer to columns in expressions, if they have characters like . or [ in them, by using _ in place of such special chars
# 2025-07-26 version
# Uses modded version of Sheet.evalExpr in sheets.py, from visidata v3.2
# This function should reexamined periodically to make sure it stays in line with the visidata source in sheets.py.
@Sheet.api
def evalExpr(self, expr:str, row=None, col=None, **kwargs):
    'eval() expr in the context of (row, col), with extra bindings in kwargs'
    if row is not None:
        # contexts are cached by sheet/rowid for duration of drawcycle
        # Only the next line is changed from visidata's default Sheet.evalExpr:
        add_expr_syms(self, kwargs)  #insert alternative names for columns into kwargs
        contexts = vd._evalcontexts.setdefault((self, self.rowid(row), col), LazyComputeRow(self, row, col, **kwargs))
    else:
        contexts = dict(sheet=self)
    return eval(expr, vd.getGlobals(), contexts)
@cache
def colname_symbol(s,
                   col_expr_translator=str.maketrans(
                    dict.fromkeys(list('.,<>()[]+-/% '), '_'))):
    return s.translate(col_expr_translator)
# modify kwargs_dict
def add_expr_syms(sheet, kwargs_dict):
    for c in sheet.columns:
        sym_name = colname_symbol(c.name)
        if sym_name != c.name and sym_name not in kwargs_dict:
            kwargs_dict.update({sym_name:c})

[cool-RR]

Great idea, and works perfectly! Thank you. I hope something like that is added to VisiData.

[ajkerrigan]

@jsvine 's normalize-columns plugin is really handy for this too.

I know you mentioned not wanting to rename, but having a command to do a wholesale rename easily/predictably makes it a bit nicer.

[cool-RR]

@ajkerrigan thanks for that reference.

[midichef]

@ajkerrigan Thanks, that normalize-columns is a clean solution to the problem.