（1）根据列表["Python","C","Scala","Java","GO","Scala","SQL","PHP","Python"]创建一个变量名为language的Series； （2）创建一个由随机整型组成的Series，要求长度与language相同，变量名为score； （3）根据language和score创建一个DataFrame； （4）输出该DataFrame的前4行数据； （5）输出该DataFrame中language字段为Python的行； （6）将DataFrame按照score字段的值进行升序排序； （7）统计language字段中每种编程语言出现的次数。

import pandas as pd
import numpy as np

# 创建Series
language = pd.Series(["Python","C","Scala","Java","GO","Scala","SQL","PHP","Python"])

# 创建随机整型Series
score = pd.Series(np.random.randint(0, 100, len(language)))

# 创建DataFrame
df = pd.DataFrame({'language':language, 'score':score})

# 输出前4行数据
print(df.head(4))

# 输出language字段为Python的行
print(df[df['language'] == 'Python'])

# 按照score字段升序排序
df = df.sort_values('score', ascending=True)

# 统计每种编程语言出现的次数
count = df['language'].value_counts()
print(count)

输出结果：

  language  score
0   Python     64
1        C     96
2    Scala     79
3     Java     72

  language  score
0   Python     64
8   Python     67

Scala      2
Python     2
C          1
SQL        1
Java       1
PHP        1
GO         1
Name: language, dtype: int64