Pandas: Sort and plot values with 2 columns

Question

I met some difficulties because I'm a real beginners with Algo and code. I've got a set of data that I want to analyze.

My objective is to have an average value of the measurement depending of the name.

I have a dataframe with two columns:

Name	Measurement value
PN1	5.4
PN2	6.5
PN3	9.6
PN2	5.4
PN4	7.4
PN2	5.4
...	...
...	...

What I want to obtain is something like that: Name with average value measurement by name :

Name	AVG Measurement value
PN1	5.4
PN2	6.5
PN3	9.6
PN4	5.4

I'm a beginners in Pandas so I need help.

I've no idea how to proceed

Answer 1

You can use groupby():

import pandas as pd

D = {
    'Name': ['PN1', 'PN2', 'PN3', 'PN2', 'PN4', 'PN2'],
    'Measurement value': [5.4, 6.5, 9.6, 5.4, 7.4, 5.4]
}


df = pd.DataFrame(D)

res = df.groupby('Name', as_index=False).mean()
res.columns = ['Name', 'AVG Measurement value']

print(res)

Prints

  Name  AVG Measurement value
0  PN1               5.400000
1  PN2               5.766667
2  PN3               9.600000
3  PN4               7.400000

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For plotting, you can use matplotlib:

import pandas as pd
import matplotlib.pyplot as plt


D = {
    'Name': ['PN1', 'PN2', 'PN3', 'PN2', 'PN4', 'PN2'],
    'Measurement value': [5.4, 6.5, 9.6, 5.4, 7.4, 5.4]
}


df = pd.DataFrame(D)


res = df.groupby('Name', as_index=False).mean()
res.columns = ['Name', 'AVG Measurement value']


plt.figure(figsize=(8, 5))
plt.bar(res['Name'], res['AVG Measurement value'], color='black')
plt.xlabel('Name')
plt.ylabel('AVG')
plt.xticks(rotation=45)
plt.tight_layout()
plt.show()

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