Researchpy : Warning in the example of summary_cont() page

Question

The researchpy's summary_cont() page there is an example and it is given as;

import numpy, pandas, researchpy

numpy.random.seed(12345678)

df = pandas.DataFrame(numpy.random.randint(10, size= (100, 2)),
                  columns= ['healthy', 'non-healthy'])
df['tx'] = ""
df['tx'].iloc[0:50] = "Placebo"
df['tx'].iloc[50:101] = "Experimental"

df['dose'] = ""
df['dose'].iloc[0:26] = "10 mg"
df['dose'].iloc[26:51] = "25 mg"
df['dose'].iloc[51:76] = "10 mg"
df['dose'].iloc[76:101] = "25 mg"

produces warning

summury_cont.py:8: SettingWithCopyWarning: 
A value is trying to be set on a copy of a slice from a DataFrame

See the caveats in the documentation: https://pandas.pydata.org/pandas-docs/stable/user_guide/indexing.html#returning-a-view-versus-a-copy
  df['tx'].iloc[0:50] = "Placebo"

This asks to see this page

Converting into this

df.loc[:, ('tx')].iloc[0:50] = "Placebo"

It still produces the same warning. What is the correct way of this?

inquirer · Accepted Answer · 2022-05-24T17:31:44.170

Values are assigned as shown below. Row indexes on the left, column names on the right. Explicit 'loc' indexing is used. You can see the difference between explicit and implicit 'iloc' indexing here

import numpy, pandas

numpy.random.seed(12345678)

df = pandas.DataFrame(data = numpy.random.randint(10, size= (100, 2)),
                  columns= ['healthy', 'non-healthy'])

df['tx'] = ""
df.loc[0:50, 'tx'] = "Placebo"
df.loc[50:101, 'tx'] = "Experimental"

df['dose'] = ""
df.loc[0:26, 'dose'] = "10 mg"
df.loc[26:51, 'dose'] = "25 mg"
df.loc[51:76, 'dose'] = "10 mg"
df.loc[76:101, 'dose'] = "25 mg"
print(df)

Output

    healthy  non-healthy            tx   dose
0         3            2       Placebo  10 mg
1         4            1       Placebo  10 mg
2         0            1       Placebo  10 mg
3         8            2       Placebo  10 mg
4         6            6       Placebo  10 mg
..      ...          ...           ...    ...
95        8            5  Experimental  25 mg
96        8            3  Experimental  25 mg
97        4            0  Experimental  25 mg
98        4            3  Experimental  25 mg
99        6            9  Experimental  25 mg

Researchpy : Warning in the example of summary_cont() page

1 Answers1