Need help understanding concept

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#1

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My Code: 

mean_happiness = {}
regions = happiness2015['Region'].unique()

for r in regions:
    happiness2015['Region'] == r
    happiness2015[r]

if this works,
happiness2015[happiness2015['Region'] == r]

how come my code way does not work? I’m just trying to understand the logic behind this.

What actually happened:

KeyError: 'Western Europe'
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#2

This is called boolean indexing here you are indexing happiness2015 with boolean values True or False. You can print print(happiness2015['Region'] == r) to confirm its values.

for more about Boolean indexing - pandas doc

While here you are indexing through raw string which gave KeyError exception if key does not found.

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#3

Thanks for the answer.

While here you are indexing through raw string which gave KeyError exception if key does not found.

But what do you mean by raw string?

#4

I mean r contains string value.