Draw a plot in which the Y-axis text data (not numeric), and X-axis numeric data

Question

I can create a simple columnar diagram in a matplotlib according to the \'simple\' dictionary:

import matplotlib.pyplot as plt
D = {u\'Label1\':26, u\'Label2\'         


        

Answer 1

Use numeric values for your y-axis ticks, and then map them to desired strings with plt.yticks():

import matplotlib.pyplot as plt
import pandas as pd 

# example data
times = pd.date_range(start='2017-10-17 00:00', end='2017-10-17 5:00', freq='H')
data = np.random.choice([0,1], size=len(times))
data_labels = ['need1','need2']

fig, ax = plt.subplots()
ax.plot(times, data, marker='o', linestyle="None")
plt.yticks(data, data_labels)
plt.xlabel("time")

Note: It's generally not a good idea to use a line graph to represent categorical changes in time (e.g. from need1 to need2). Doing that gives the visual impression of a continuum between time points, which may not be accurate. Here, I changed the plotting style to points instead of lines. If for some reason you need the lines, just remove linestyle="None" from the call to plt.plot().

UPDATE
(per comments)

To make this work with a y-axis category set of arbitrary length, use ax.set_yticks() and ax.set_yticklabels() to map to y-axis values.

For example, given a set of potential y-axis values labels, let N be the size of a subset of labels (here we'll set it to 4, but it could be any size).

Then draw a random sample data of y values and plot against time, labeling the y-axis ticks based on the full set labels. Note that we still use set_yticks() first with numerical markers, and then replace with our category labels with set_yticklabels().

labels = np.array(['A','B','C','D','E','F','G'])
N = 4

# example data
times = pd.date_range(start='2017-10-17 00:00', end='2017-10-17 5:00', freq='H')
data = np.random.choice(np.arange(len(labels)), size=len(times))

fig, ax = plt.subplots(figsize=(15,10))
ax.plot(times, data, marker='o', linestyle="None")
ax.set_yticks(np.arange(len(labels)))
ax.set_yticklabels(labels)
plt.xlabel("time")