List all columns of a DataFrame that contain a certain character at least once.

search-pandas-columns-for-string.py

import pandas as pd

# Input:
#            a     b        c    d    e
# 0  Text       Text  NaN      0.0  5
# 1  Text       NaN   1.1.1.1  0.0  55
# 2  Text.Text  Text  Text     0.4  555

data = [
    {"a": "Text", "b": "Text", "d": 0, "e": 5},
    {"a": "Text", "c": "1.1.1.1", "d": 0, "e": 55},
    {"a": "Text.Text", "b": "Text", "c": "Text", "d": 0.4, "e": 555},
]

df = pd.DataFrame(data)
[c for c in df.columns if (df[c].astype(str).str.find(".") > -1).any()]

# Output:
# ['a', 'd', 'c']