Python: vlookup on complex arrays searching through multiple columns for each row -

i have following problem python code doesn't work. hoping suggestions on why , how resolve.

here's example dataframe:

 cust_id max_nibt nibt_0 nibt_1  nibt_10 line_0  line_1  line_10 11  200 -5  200 500 100 200 300 22  300 -10 100 300 100 200 300 33  400 -20 0   400 100 200 300 

for in range (0,11):     if (df4['nibt_%s' % i] == df4['max_nibt']):          df4['model_line'] = df4['line_%s' % i] 

the code gives me following error:

valueerror: truth value of series ambiguous. use a.empty, a.bool(), a.item(), a.any() or a.all()

however, when use .any(), gives me last range assigning model_line = line_10. when use .all(), answer same cust_ids. thoughts? in advance.

i have guess @ want, not using pd.series correctly... see here better explanation.

iiuc:
want fill in values line_x when nibt_x equals max_nibt

# filter `nibt` columns , find first column equals max nibt_maxes = df.filter(regex='nibt_\d+').eq(df.max_nibt, 0).idxmax(1)  # swap out string `nibt` `line` lines = nibt_maxes.replace('nibt', 'line', regex=true)  # use `lookup` , assign values df['model'] = df.lookup(lines.index, lines.values)     cust_id  max_nibt  nibt_0  nibt_1  nibt_10  line_0  line_1  line_10  model 0       11       200      -5     200      500     100     200      300    200 1       22       300     -10     100      300     100     200      300    300 2       33       400     -20       0      400     100     200      300    300