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================ by Jawad Haider

05 - Operations

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Operations

There are lots of operations with pandas that will be really useful to you, but don’t fall into any distinct category. Let’s show them here in this lecture:

import pandas as pd
df = pd.DataFrame({'col1':[1,2,3,4],'col2':[444,555,666,444],'col3':['abc','def','ghi','xyz']})
df.head()
col1 col2 col3
0 1 444 abc
1 2 555 def
2 3 666 ghi
3 4 444 xyz

Info on Unique Values

df['col2'].unique()

array([444, 555, 666])

df['col2'].nunique()

3

df['col2'].value_counts()

444    2
555    1
666    1
Name: col2, dtype: int64

Selecting Data

#Select from DataFrame using criteria from multiple columns
newdf = df[(df['col1']>2) & (df['col2']==444)]

newdf
col1 col2 col3
3 4 444 xyz

Applying Functions

def times2(x):
    return x*2

df['col1'].apply(times2)

0    2
1    4
2    6
3    8
Name: col1, dtype: int64

df['col3'].apply(len)

0    3
1    3
2    3
3    3
Name: col3, dtype: int64

df['col1'].sum()

10

Permanently Removing a Column

del df['col1']

df
col2 col3
0 444 abc
1 555 def
2 666 ghi
3 444 xyz

Get column and index names:

df.columns

Index(['col2', 'col3'], dtype='object')

df.index

RangeIndex(start=0, stop=4, step=1)

Sorting and Ordering a DataFrame:

df
col2 col3
0 444 abc
1 555 def
2 666 ghi
3 444 xyz 
df.sort_values(by='col2') #inplace=False by default
col2 col3
0 444 abc
3 444 xyz
1 555 def
2 666 ghi

Great Job! Thats the end of this part.

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