Python數據分析實戰【第三章】2.18-Pandas去重及替換【python】

【課程2.18】 去重及替換

1.去重 .duplicated

.duplicated / .replace

s = pd.Series([1,1,1,1,2,2,2,3,4,5,5,5,5])
print(s.duplicated())
print(s[s.duplicated() == False])
print('-----')
# 判斷是否重複
# 通過布爾判斷，得到不重複的值

#通過unique也可以
sr2 = sr1.unique()#不重複的列表
sr = pd.Series(sr2)#以列表生成Series
print(sr)

s_re = s.drop_duplicates()
print(s_re)
print('-----')
# drop.duplicates移除重複
# inplace參數：是否替換原值，默認False

df = pd.DataFrame({'key1':['a','a',3,4,5],
                  'key2':['a','a','b','b','c']})
print(df.duplicated())#按行判斷
print(df['key2'].duplicated())
# Dataframe中使用duplicated
----------------------------------------------------------------------
0     False
1      True
2      True
3      True
4     False
5      True
6      True
7     False
8     False
9     False
10     True
11     True
12     True
dtype: bool
0    1
4    2
7    3
8    4
9    5
dtype: int64
-----
0    1
4    2
7    3
8    4
9    5
dtype: int64
-----
0    False
1     True
2    False
3    False
4    False
dtype: bool
0    False
1     True
2    False
3     True
4    False
Name: key2, dtype: bool

3.替換 .replace

s = pd.Series(list('ascaazsd'))
print(s.replace('a', np.nan))
print(s.replace(['a','s'] ,np.nan))
print(s.replace({'a':'hello world!','s':123}))
# 可一次性替換一個值或多個值
# 可傳入列表或字典
----------------------------------------------------------------------
0    NaN
1      s
2      c
3    NaN
4    NaN
5      z
6      s
7      d
dtype: object
0    NaN
1    NaN
2      c
3    NaN
4    NaN
5      z
6    NaN
7      d
dtype: object
0    hello world!
1             123
2               c
3    hello world!
4    hello world!
5               z
6             123
7               d
dtype: object