Data Manipulation¶

Questions¶

Problem: [GOOGLE] Score Bucketization

Let’s say you’re given a list of standardized test scores from high schoolers from grades 9 to 12.

Given the dataset, write code in Pandas to return the cumulative percentage of students that received scores within the buckets of $<50, <75, <90, <100$ .

Example Input:

user_id	grade	test score
1	10	85
2	10	60
3	11	90
4	10	30
5	11	99

Example Output:

grade	test score	percentage
10	<50	30%
10	<75	65%
10	<90	96%
10	<100	99%
11	<50	15%
11	<75	50%

import pandas as pd
import numpy as np

df = pd.DataFrame([[1,10,85],[2,10,60],[3,11,90],[4,10,30],[5,11,99]], columns = ["user_id","grade","test score"])

df["<50"] = np.where(df["test score"]<50,1,0)
df["<75"] = np.where(df["test score"]<75,1,0)
df["<90"] = np.where(df["test score"]<90,1,0)
df["<100"] = np.where(df["test score"]<100,1,0)

df = df.groupby(["grade"])[["<50","<75","<90","<100"]].sum().reset_index()
df = df.melt(id_vars=["grade"],var_name="test score",value_name="count")

df["grp_ttl"] = df.groupby("grade")["count"].transform('max')
df["percentage"] = 100*df["count"]/df["grp_ttl"]

df = (df[["grade","test score","percentage"]].copy()).sort_values(["grade","percentage"],ascending=True)

df["percentage"] = df.percentage.astype(int).astype(str)
df["percentage"] = df["percentage"] + "%"

df.head(10)

Problem: [NEXTDOOR] Complete Addresses

You’re given two dataframes. One contains information about addresses and the other contains relationships between various cities and states:

df_addresses

address

4860 Sunset Boulevard, San Francisco, 94105 3055 Paradise Lane, Salt Lake City, 84103 682 Main Street, Detroit, 48204 9001 Cascade Road, Kansas City, 64102 5853 Leon Street, Tampa, 33605

df_cities

city state Salt Lake City Utah Kansas City Missouri Detroit Michigan Tampa Florida San Francisco California

Write a function complete_address to create a single dataframe with complete addresses in the format of street, city, state, zipcode.

Input:

import pandas as pd

addresses = {“address”: [“4860 Sunset Boulevard, San Francisco, 94105”, “3055 Paradise Lane, Salt Lake City, 84103”, “682 Main Street, Detroit, 48204”, “9001 Cascade Road, Kansas City, 64102”, “5853 Leon Street, Tampa, 33605”]}

cities = {“city”: [“Salt Lake City”, “Kansas City”, “Detroit”, “Tampa”, “San Francisco”], “state”: [“Utah”, “Missouri”, “Michigan”, “Florida”, “California”]}

df_addresses = pd.DataFrame(addresses) df_cities = pd.DataFrame(cities)

Output:

def complete_address(df_addresses,df_cities) ->

address 4860 Sunset Boulevard, San Francisco, California, 94105 3055 Paradise Lane, Salt Lake City, Utah, 84103 682 Main Street, Detroit, Michigan, 48204 9001 Cascade Road, Kansas City, Missouri, 64102 5853 Leon Street, Tampa, Florida, 33605

import pandas as pd

addresses = {"address": ["4860 Sunset Boulevard, San Francisco, 94105", "3055 Paradise Lane, Salt Lake City, 84103", "682 Main Street, Detroit, 48204", "9001 Cascade Road, Kansas City, 64102", "5853 Leon Street, Tampa, 33605"]}

cities = {"city": ["Salt Lake City", "Kansas City", "Detroit", "Tampa", "San Francisco"], "state": ["Utah", "Missouri", "Michigan", "Florida", "California"]}

df_addresses = pd.DataFrame(addresses)
df_cities = pd.DataFrame(cities)


def complete_address(df_addresses,df_cities):
    temp = df_addresses['address'].str.split(", ", n = 4, expand = True)
    temp.columns = ['street','city','zip']
    temp = temp.merge(df_cities, on=["city"], how="inner")
    temp["final"] = temp[["street","city","state","zip"]].apply(lambda x: (", ").join(x), axis = 1)
    temp = temp[["final"]].copy()
    temp.columns = ["address"]
    return temp

complete_address(df_addresses,df_cities)

Problem: PANDAS vs SQL

Can you tell me what is approximately Windows function equivalent in Pandas?

Solution:

Windows function in SQL brings row wise calculation capabilities. An approximate equivalent of it can be transform in pandas it brings row wise calculation capabilities in Python.