7.2 Sort the structured data
1. Single-field sorting
2. Multi-field sorting
3. Position after sorting
4. Random sorting
SPL
A | B | |
---|---|---|
1 | =file(“EMPLOYEE.csv”).import@tc() | |
2 | =A1.sort(BIRTHDAY) | /Sort by birthday in ascending order |
3 | =A1.sort([BIRTHDAY,-HIREDATE]) | /Sort by birthday in ascending order and by hire date in descending order |
4 | =A1.psort@z(SALARY) | /Position after sorting by salary in descending order |
5 | =A1.sort(rand()) | /Random sorting |
SQL
1. Single-field sorting
SELECT *
FROM EMPLOYEE
ORDER BY BIRTHDAY;
2. Multi-field sorting
SELECT *
FROM EMPLOYEE
ORDER BY BIRTHDAY ASC,HIREDATE DESC;
3. Position after sorting
SELECT rn,SALARY
FROM(SELECT EMP.*,ROWNUM AS rn
FROM (SELECT * FROM EMPLOYEE ORDER BY EID) EMP)
ORDER BY SALARY DESC;
4. Random sorting
SELECT *
FROM EMPLOYEE
ORDER BY dbms_random.value;
Python
df = pd.read_csv('../EMPLOYEE.csv')
#Sort by birthday in ascending order
sorted_by_birthday = df.sort_values('BIRTHDAY')
#Sort by birthday in ascending order and by hire date in descending order
sorted_by_birthday_hiredate = df.sort_values(['BIRTHDAY', 'HIREDATE'], ascending=[True, False])
#Position after sorting by salary in descending order
sorted_positions = np.argsort(-df['SALARY'].values)
#Random sorting
random_sorted = df.sample(frac=1, random_state=42)
7.3 Rank a sequence
Example codes for comparing SPL, SQL, and Python
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