pandas如何选择列,删除列,增加列,按照条件筛选行

选择列

import pandas as pd

data = {'a': [0, 1], 'b': ['x', 'y'], 'c': [5, 6]}
df = pd.DataFrame(data)
new_df = df[['a', 'b']]
print(new_df)

删除列

import pandas as pd

data = {'a': [0, 1], 'b': ['x', 'y'], 'c': [5, 6]}
df = pd.DataFrame(data)
# 方法1
del df['a']
print(df)
# 方法2
df.drop(['c'], axis=1, inplace=True)
print(df)

其中axis=1表示筛选列,inplace = True表示在原Dataframe上修改,默认为False,也可以写为

df = df.drop(['c'], axis=1)

增加列或者替换整列

# 增加列或者替换整列
df['a'] = [0, 1]
df['c'] = [5, 6]
df['b'] = ['y', 'x']
print(df)

按条件筛选

# 按条件筛选
new_df = df[df['a'].isin([1])]
print(new_df)

表示选'a'为1的行

整个代码

import pandas as pd

# 选择列
data = {'a': [0, 1], 'b': ['x', 'y'], 'c': [5, 6]}
df = pd.DataFrame(data)
new_df = df[['a', 'b']]
print(new_df)
# 删除列
del df['a']
print(df)
df.drop(['c'], axis=1, inplace=True)
print(df)
# 增加列或者替换整列
df['a'] = [0, 1]
df['c'] = [5, 6]
df['b'] = ['y', 'x']
print(df)
# 按条件筛选
new_df = df[df['a'].isin([1])]
print(new_df)