Python for Visualization

Question 1

Pandas function that converts column to datetime type and return a series object

Answer 1

dataframe[‘col’] = pandas.to_datetime(df[‘col’])

Question 2

Library used to create charts

Answer 2

matplotlib

Question 3

matplotlib module that provides a high-level interface that allows us to quickly create common data plots and perform common tweaks to them

Answer 3

pyplot

Question 4

Code to import pyplot module

Answer 4

import matplotlib.pyplot as plt

Question 5

pyplot functions to (1) create chart and (2) display

Answer 5

plt. plot(x_values, y_values, c=’color’, label=’label’)
plt. show()

For x and y values, matplotlib will accept any iterable object, like NumPy arrays and pandas.Series instances

Question 6

pyplot function to customize behavior of x-axis ticks

Answer 6

plt.xticks()

Question 7

pyplot function to modify x-axis labels

Answer 7

plt.xlabel()

accepts a string value, which gets set as the x-axis label

Question 8

pyplot function to modify y-axis labels

Answer 8

plt.ylabel()

accepts a string value, which is set as the y-axis label

Question 9

pyplot function to modify chart title

Answer 9

plt.title()

accepts a string value, which is set as the plot title

Question 10

pyplot function to manually create a figure

A figure acts as a container for all plots and has methods for customizing the appearance and behavior for the plots within that container.

Answer 10

fig = plt.figure()

Question 11

Method to add a subplot to an existing figure, which will return a new axes object that needs to be assigned to a variable

Answer 11

axes_obj = fig.add_subplot(nrows, ncols, plot_number)

Question 12

Creating a figure with 2 plots, one above the other

Answer 12

ax1 = fig.add_subplot(2,1,1)
ax2 = fig.add_subplot(2,1,2)

Question 13

Parameter to adjust dimensions of the plotting area

Answer 13

figsize (use when calling plt.figure())

fig = plt.figure(figsize=(width, height))

Width & height are in inches

Question 14

Method to add a title to axes object

Answer 14

axes. set_title

ax1. set_title(‘Chart Name’)

Question 15

Built in type that represents an immutable sequence of numbers and is commonly used for looping a specific number of times in for loops

Answer 15

range(start, stop[, step])

Ex: for i in range(5)
Produces a sequence of integers starting at zero, and going up to (but not including) the argument’s value

Question 16

pyplot function to create a legend

Answer 16

plt.legend(loc=’upper left’)

Question 17

Method to place a legend on the axes

Answer 17

axes.legend

Question 18

pyplot function to create a bar chart

Answer 18

plt.bar() or axes.bar(left=[position], height=[height], width=[width])

axes.bar allows easier customization
Ex: ax.bar(left=bar_positions, height=bar_heights, width=.5)

Question 19

Shortcut to generate a single subplot and return both the figure and axes object

Answer 19

fig, ax = plt.subplots()

Question 20

numpy function that returns evenly spaces values

Answer 20

np.arange([number of values to generate])

Ex:
from numpy import arange
bar_positions = arange(5) + .75

Question 21

Method to change positions of x ticks

Answer 21

axes.set_xticks()

Ex:
tick_positions = range(1,6)
ax.set_xticks(tick_positions)

Question 22

Method to specify tick labels

Answer 22

axes.set_xticklabels()

Ex:
num_cols = [list]
ax.set_xticklabels(num_cols)

Question 23

pyplot function to create a bar chart

Answer 23

axes.barh(bottom=[y coord], width=[length of bars])

Question 24

Methods to specify axes labels

Answer 24

axes. set_xlabel

axes. set_ylabel

Question 25

___ to generate scatter plot

Answer 25

axes.scatter(x=’x_values’, y=’y_values’)

Question 26

Sets data limits for axes

Answer 26

axes. setxlim(min, max)

axes. setylim(min, max)

Question 27

Method to generate a histogram

Answer 27

axes. hist()

ax. hist(df[‘col’], bins=10, range=(0, 5))

Question 28

Method to generate a boxplot

Answer 28

axes.boxplot()

ax. boxplot(norm_reviews[‘RT_user_norm’])
ax. set_xticklabels([“Rotten Tomatoes”])