DataFrame: How to toggle a cell value base on another cell of the row?

Question

I have a list of friends attending my party:

import pandas as pd
d = {'name': ['Alice', 'Bob', 'Charlie'], 'is_here': [True, True, False]}
df = pd.DataFrame(data=d)

Question: How can I toggle the is_here boolean based on a given name? (e.g. how to make toggle('Charlie') turns the False into True in my DataFrame?)

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I can get one's status as a boolean using df[df['name'] == 'Charlie'].iloc[0]['is_here'], but I struggle changing the value in df.

Answer 1

Toggle Charlie with xor

df.loc[df.name.eq('Charlie'), 'is_here'] ^= True

df

   is_here     name
0     True    Alice
1     True      Bob
2     True  Charlie

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Explanation

Only one can be True
Truth Table for xor

       x      y  x ^ y
0   True   True  False
1   True  False   True
2  False   True   True
3  False  False  False

So:
if x = True, x ^ True evaluates to False
if x = False, x ^ True evaluates to True

Using ^= on the loc, we take the xor with True for all elements represented with the slice and assign the results in place.

Answer 2

To update your mapping

df = df.set_index('name')
df.loc['Charlie', 'is_here'] = ~df.loc['Charlie', 'is_here']

print(df.reset_index())

#       name  is_here
# 0    Alice     True
# 1      Bob     True
# 2  Charlie     True

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To query your mapping

From your dataframe:

ishere = df.set_index('name')['is_here'].get

print(ishere('Alice'))  # True

From your original dictionary:

ishere = dict(zip(d['name'], d['is_here'])).get

print(ishere('Alice'))  # True