python IndexError: boolean index did not match indexed array along dimension 0; dimension is 32 but corresponding boolean dimension is 112

Question

i am new to matploblib and numpy and have faced issues trying to extracting the data. the following codes results in IndexError: boolean index did not match indexed array along dimension 0; dimension is 32 but corresponding boolean dimension is 112. pls advise!!

dataset used: https://data.gov.sg/dataset/monthly-motor-vehicle-population-by-type-of-fuel-used

import numpy as np
import matplotlib.pyplot as plt
title = "motor-vehicle-population-statistics-by-type-of-fuel-used."
titlelen = len(title)
print("{:*^{titlelen}}".format(title, titlelen=titlelen+6))
print()
data = np.genfromtxt("data/motor-vehicle-population-statistics-by-type-of-fuel-used.csv",
                      dtype=("datetime64[Y]","U100","U110",int),
                      delimiter=",",
                      names=True)

years = np.unique(data["month"])
category = np.unique(data['category'])
type = np.unique(data['type'])

cars = data[data["category"]=="Cars"]["number"]
carspetrol = cars[data["type"]=="Petrol"]["number"]
# print(cars)
print(carspetrol)

In my experience, whenever the whole error string indicated in the title of this question is raised (IndexError: boolean index did not match indexed array along dimension 0; dimension is X but corresponding boolean dimension is Y), it means you are trying to do an operation which requires two arrays to have the same dimensions, but they don't. — Tms91
– Tms91, Commented Jul 9, 2023 at 14:39

Tms91 · Accepted Answer · 2023-07-09 14:32:20Z

2

you have few issues here..

first one don't use python keywords as variables change this

type = np.unique(data['type'])

to this

types = np.unique(data['type'])

your error is you are trying to compare a boolean array which has 112 values (data) with a 32-elements array (cars). So your code should change like this

cars = data[data["category"]=="Cars"]
carspetrol = cars[cars["type"]=="Petrol"]["number"]

furthermore, it is better to use analytical library like Pandas to do the basic analytics than numpy.

edited Jul 9, 2023 at 14:32

Tms91

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answered Nov 19, 2019 at 2:54

Rajith Thennakoon

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