Case Study (autos) : Converting datatypes¶

import pandas as pd
import numpy as np

df = pd.read_csv('carsinfo.csv')

Replacing "?" with "nan"¶

As we discussd before, we should handle "?" for following columns before converting their datatypes:

normalized_losses     object

bore                  object

stroke                object

horsepower            object

peak_rpm              object

price                 object

Therefore, let's Get rid of "?" , replace it with "Nan" , and then convert datatypes

Replacing "?" with "nan" and converting datatypes¶

df["normalized_losses"] = df["normalized_losses"].replace({'?': np.nan}).dropna().astype(int)
df["bore"] = df["bore"].replace({'?': np.nan}).dropna().astype(float)
df["stroke"] = df["stroke"].replace({'?': np.nan}).dropna().astype(float)
df["horsepower"] = df["horsepower"].replace({'?': np.nan}).dropna().astype(float)
df["peak_rpm"] = df["peak_rpm"].replace({'?': np.nan}).dropna().astype(float)
df["price"] = df["price"].replace({'?': np.nan}).dropna().astype(float)

df.head()

# Let's check datatypes again to see modifications

df.dtypes

symboling              int64
normalized_losses    float64
make                  object
fuel_type             object
aspiration            object
num_of_doors          object
body_style            object
drive_wheels          object
engine_location       object
wheel_base           float64
length               float64
width                float64
height               float64
curb_weight            int64
engine_type           object
num_of_cylinders      object
engine_size            int64
fuel_system           object
bore                 float64
stroke               float64
compression_ratio    float64
horsepower           float64
peak_rpm             float64
city_mpg               int64
highway_mpg            int64
price                float64
dtype: object

	symboling	normalized_losses	make	fuel_type	aspiration	num_of_doors	body_style	drive_wheels	engine_location	wheel_base	...	engine_size	fuel_system	bore	stroke	compression_ratio	horsepower	peak_rpm	city_mpg	highway_mpg	price
0	3	NaN	alfa-romero	gas	std	two	convertible	rwd	front	88.6	...	130	mpfi	3.47	2.68	9.0	111.0	5000.0	21	27	13495.0
1	3	NaN	alfa-romero	gas	std	two	convertible	rwd	front	88.6	...	130	mpfi	3.47	2.68	9.0	111.0	5000.0	21	27	16500.0
2	1	NaN	alfa-romero	gas	std	two	hatchback	rwd	front	94.5	...	152	mpfi	2.68	3.47	9.0	154.0	5000.0	19	26	16500.0
3	2	164.0	audi	gas	std	four	sedan	fwd	front	99.8	...	109	mpfi	3.19	3.40	10.0	102.0	5500.0	24	30	13950.0
4	2	164.0	audi	gas	std	four	sedan	4wd	front	99.4	...	136	mpfi	3.19	3.40	8.0	115.0	5500.0	18	22	17450.0