在Lambda Python中使用两个变量
我想基于两个变量创建一个新列。如果第1列>=0.5或第2列<0.5且第1列<0.5或第2列>=0.5,则我希望新列的值为Good,否则为Bad 我试过使用lambda和if在Lambda Python中使用两个变量,python,pandas,lambda,Python,Pandas,Lambda,我想基于两个变量创建一个新列。如果第1列>=0.5或第2列
将行传递到lambda中
df['new column'] = df[['column 1', 'column 2']].apply(lambda row: "Good" if (row['column 1'] >= .5 or row['column 2'] < .5) and (row['column 1'] < .5 or row['column 2'] >= .5) else "Bad", axis=1)
将行传递到lambda中
df['new column'] = df[['column 1', 'column 2']].apply(lambda row: "Good" if (row['column 1'] >= .5 or row['column 2'] < .5) and (row['column 1'] < .5 or row['column 2'] >= .5) else "Bad", axis=1)
试试这个:
import pandas as pd
def update_column(row):
if (row['x'] >= .5 or row['y'] <= .5) and (row['x'] < .5 or row['y'] >= .5):
return "Good"
return "Bad"
df['new_column'] = df.apply(update_column, axis=1)
试试这个:
import pandas as pd
def update_column(row):
if (row['x'] >= .5 or row['y'] <= .5) and (row['x'] < .5 or row['y'] >= .5):
return "Good"
return "Bad"
df['new_column'] = df.apply(update_column, axis=1)
使用np。其中,pandas进行内部数据对齐,这意味着您不需要使用apply或逐行迭代,pandas将对齐索引上的数据:
df['new column'] = df['new column'] = np.where(((df['y'] <= .5) | (df['x'] > .5)) & ((df['x'] < .5) | (df['y'] >= .5)), 'Good', 'Bad')
df
时间:
每个回路5.83 ms±484µs,平均值±标准偏差为7次运行,每个回路100次
使用np。其中,pandas进行内部数据对齐,这意味着您不需要使用apply或逐行迭代,pandas将对齐索引上的数据:
df['new column'] = df['new column'] = np.where(((df['y'] <= .5) | (df['x'] > .5)) & ((df['x'] < .5) | (df['y'] >= .5)), 'Good', 'Bad')
df
时间:
每个回路5.83 ms±484µs,平均值±标准偏差为7次运行,每个回路100次
如果有矢量化选项,为什么要循环?当然,有几种不同的方法可以解决这个问题。但是循环通常要慢得多,而且应用比python循环快得多。这里是DataFrame.where方法,该方法速度更快,表现力更强。从长远来看,如果有一个向量化选项,那么了解工具why loop也是值得的?当然,有几种不同的方法可以解决这个问题。但是循环通常要慢得多,而且apply比python循环快得多。这里是DataFrame.where方法,该方法速度更快,表现力更强。从长远来看,了解这些工具也是值得的
df['new column'] = df['new column'] = np.where(((df['y'] <= .5) | (df['x'] > .5)) & ((df['x'] < .5) | (df['y'] >= .5)), 'Good', 'Bad')
df
import pandas as pd
df = pd.DataFrame({'x': [1, 2, 0.1, 0.1],
'y': [1, 2, 0.7, 0.2],
'column 3': [1, 2, 3, 4]})
df['new column'] = df['new column'] = np.where(((df['y'] <= .5) | (df['x'] > .5)) & ((df['x'] < .5) | (df['y'] >= .5)), 'Good', 'Bad')
df
x y column 3 new column
0 1.0 1.0 1 Good
1 2.0 2.0 2 Good
2 0.1 0.7 3 Bad
3 0.1 0.2 4 Good
import pandas as pd
import numpy as np
np.random.seed(123)
df = pd.DataFrame({'x':np.random.random(100)*2,
'y': np.random.random(100)*1})
def update_column(row):
if (row['x'] >= .5 or row['y'] <= .5) and (row['x'] < .5 or row['y'] >= .5):
return "Good"
return "Bad"
%timeit df['new column'] = np.where(((df['y'] <= .5) | (df['x'] > .5))
& ((df['x'] < .5) | (df['y'] >= .5)), 'Good', 'Bad')
%timeit df['new_column'] = df.apply(update_column, axis=1)