Python interview in 48 hours? Revise only this.

1-5: core Python and functions

1. 01

   List, tuple, dict, set

   List changes. Tuple doesn't. Dict maps keys. Set drops duplicates.

   cities = ["Pune", "Patna"]
   emp = {"name": "Riya", "age": 24}
   unique = set([1, 2, 2, 3])

2. 02

   List comprehension

   Filter and transform in one line.

   [x * 2 for x in nums if x > 0]

3. 03

   Count with a dict

   The classic word-count question.

   counts = {}
   for w in words:
       counts[w] = counts.get(w, 0) + 1

4. 04

   Clean a string

   strip, lower, split. Chain them.

   [c.strip().lower() for c in s.split(",")]

5. 05

   Function with a default

   pct is optional. Say this out loud.

   def bonus(sal, pct=10):
       return sal * pct / 100

6-10: pandas

1. 06

   First look at data

   Shape, types, nulls, summary.

   df.head()
   df.info()
   df.describe()

2. 07

   Filter rows with loc

   Condition first, then columns.

   df.loc[df["salary"] > 60000, ["id", "salary"]]

3. 08

   Group and aggregate

   Named outputs read cleanly.

   df.groupby("dept").agg(
       avg=("salary", "mean"),
       n=("id", "count"))

4. 09

   Merge two tables

   how="left" keeps every row of df.

   pd.merge(df, cities, on="id", how="left")

5. 10

   Handle missing values

   Count first. Then fill or drop.

   df.isna().sum()
   df["city"].fillna("Unknown")

5 questions they actually ask

More time? Try the 12 Python programs interviewers love and the pandas cheat sheet.