Labeling points in matplotlib scatterplot [duplicate]

Question

Edit: This question is not a duplicate, I don't want to plot numbers instead of points, I wanted to plot numbers beside my points.

I'm making a plot using matplotlib. There are three points to plot [[3,9],[4,8],[5,4]]

I can easily make a scatterplot with them

import matplotlib.pyplot as plt

allPoints = [[3,9],[4,8],[5,4]]

f, diagram = plt.subplots(1)

for i in range(3):
    xPoint =  allPoints[i][0]
    yPoint =  allPoints[i][1]
    diagram.plot(xPoint, yPoint, 'bo')

That produces this plot:

I want to label each point with numbers 1,2,3.

Based on this SO answer I tried to use annotate to label each point.

import matplotlib.pyplot as plt

allPoints = [[1,3,9],[2,4,8],[3,5,4]]

f, diagram = plt.subplots(1)

for i in range(3):
    pointRefNumber = allPoints[i][0]
    xPoint =  allPoints[i][1]
    yPoint =  allPoints[i][2]
    diagram.annotate(pointRefNumber, (xPoint, yPoint))

This produces a blank plot. I'm closely following the other answer but it isn't producing any plot. Where have I made a mistake?

Since you already know how to plot points, and you already know how to label points, the only open question was why the plot with only annotations stays empty. This is answered in the first duplicate question. For the general case of labeling points, I added another duplicate. — ImportanceOfBeingErnest
– ImportanceOfBeingErnest, Commented Jul 10, 2017 at 10:21
@ImportanceOfBeingErnest I didn't know how to plot labeled points. I thought the .annotate() feature would both plot and label points. To me that made sense because I was specifying coordinates and labels, but I was wrong. — Hugh
– Hugh, Commented Jul 10, 2017 at 10:42

glegoux · Accepted Answer · 2017-07-09 16:36:02Z

20

You can do that:

import matplotlib.pyplot as plt

points = [[3,9],[4,8],[5,4]]

for i in range(len(points)):
    x = points[i][0]
    y = points[i][1]
    plt.plot(x, y, 'bo')
    plt.text(x * (1 + 0.01), y * (1 + 0.01) , i, fontsize=12)

plt.xlim((0, 10))
plt.ylim((0, 10))
plt.show()

answered Jul 9, 2017 at 16:36

glegoux

3,62317 silver badges32 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Hugh Over a year ago

That works out better, the text using .annotate() is too small so it's helpful to be able to increase the size

Hugh · Accepted Answer · 2017-07-09 16:46:23Z

8

I solved my own question. I needed to plot the points and then annotate them, the annotation does not have plotting built-in.

import matplotlib.pyplot as plt

allPoints = [[1,3,9],[2,4,8],[3,5,4]]

f, diagram = plt.subplots(1)

for i in range(3):
    pointRefNumber = allPoints[i][0]
    xPoint =  allPoints[i][1]
    yPoint =  allPoints[i][2]
    diagram.plot(xPoint, yPoint, 'bo')
    diagram.annotate(nodeRefNumber, (xPoint, yPoint), fontsize=12)

Edited to add the fontsize option just like in Gregoux's answer

edited Jul 9, 2017 at 16:46

answered Jul 9, 2017 at 16:30

Hugh

4431 gold badge5 silver badges12 bronze badges

Collectives™ on Stack Overflow

Labeling points in matplotlib scatterplot [duplicate]

2 Answers 2

1 Comment

Comments

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

Comments

Linked

Related