Matplotlib Name points on plots

Question

I have searched and found that using annotate in matplotlib for jupyter, we can name the x and y of a point.

I have retried doing as you suggested.

import matplotlib.pyplot as plt
import pandas as pd

def fit_data():

    fig = plt.figure(1,figsize=(20,6))
    plt.subplot(111)

    data1 = pd.DataFrame({"ID" : list(range(11)), 
                   "R" : list(range(11)),
                   "Theta" : list(range(11))})

    plt.scatter(data1['R'], data1['Theta'],  marker='o', color='b', s=15)

    for i, row in data1.iterrows():
        plt.annotate(row["ID"], xy=(row["R"],row["Theta"]))

    plt.xlabel('R',size=20)
    plt.ylabel('Theta',size=20)

    plt.show()
    plt.close()

fit_data()

It still doesn't take the ID from my data. It is still plotting an arbitrary plot. this is the image after using the revised code

My data is as follows

1 19.177    24.642
2 9.398     12.774
3 9.077     12.373
4 15.287    19.448
5 4.129     5.41
6 2.25      3.416
7 11.674    15.16
8 10.962    14.469
9 1.924     3.628
10 2.087    3.891
11 9.706    13.186

The syntax for annotate is ax.annotate("text", xy=(x,y)). Instead of "text" you can use your ID. Feel free to provide a code with your attempt and an explanation at which point you are stuck. — ImportanceOfBeingErnest
– ImportanceOfBeingErnest, Commented Aug 3, 2018 at 12:46

ImportanceOfBeingErnest · Accepted Answer · 2018-08-03 13:27:15Z

1

I suppose the confusion comes from the fact that while scatter can plot all points at once, while an annotation is a singular object. You would hence need one annotation per row in the dataframe.

import matplotlib.pyplot as plt
import pandas as pd

df = pd.DataFrame({"ID" : list(range(6)),          # Do not copy this part.
                   "R" : [5,4,1,2,3,4],            # Use your own data 
                   "Theta" : [20,15,40,60,51,71]}) # instead.

fig = plt.figure(1,figsize=(20,6))
plt.subplot(111)

plt.scatter(df['R'], df['Theta'],  marker='o', color='b', s=15)

for i, row in df.iterrows():
    plt.annotate(row["ID"], xy=(row["R"],row["Theta"]))

plt.xlabel('R',size=20)
plt.ylabel('Theta',size=20)

plt.show()

edited Aug 3, 2018 at 13:27

answered Aug 3, 2018 at 13:07

ImportanceOfBeingErnest

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11 Comments

BRMBU Over a year ago

Thank you. The ID that it marks is from '0' not from my data set. If I have a large data set say 100 odd points, then do I have to do the 'df = pd.DataFrame({"ID" : list(range(6)), "R" : [5,4,1,2,3,4], "Theta" : [20,15,40,60,51,71]})' for all those points.

ImportanceOfBeingErnest Over a year ago

No. I created a dataset df here because I do not have your data. In your case you will use your own data of course.

BRMBU Over a year ago

I have edited the question putting in the trail data set I am using. It has to use the ID mentioned in the file and not an arbitrary one. How do I go about doing that

ImportanceOfBeingErnest Over a year ago

Instead of the dataset df I used here, you need to use your own dataset data1.

BRMBU Over a year ago

Pardon me I didn't follow. Could you please explain.

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