How can this for loop code work? (pandas, jupyter, python)

Question

i am a student working in bioinformatics using scanpy, python. During finding marker genes, i was going to make a data frame. The following is the code.

pd.DataFrame({group + '_' + key[:1] : result[key][group] for group in groups for key in ['names', 'pvals']}).head(5)

My question here are two:

the for statement does not have a ':' mark
and the naming of the 'group' and 'key' is done after, how does it affect the previous one(group + '_' + key[:1] : result[key][group])?

I want to understand the code.

This is a special syntax that replaces a classical loop. As said above it is called a "*dictionary comprehension*". — mozway, Jan 14 '23 at 05:15

score 0 · Answer 1 · answered Jan 14 '23 at 04:43

0

What exists in Python is that in order to create and use the list, it is not important be named before use. Just taking a name from it while working is enough for Python

answered Jan 14 '23 at 04:43

ArminDM

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Then do you mean that the order in which variables are created and used does not matter? – JJUN Jan 14 '23 at 04:49
@JJUN you can ignore this answer, it is incorrect. Read about dictionary comprehensions – mozway Jan 14 '23 at 06:09

How can this for loop code work? (pandas, jupyter, python)

1 Answers1