[英]pandas new column with condition
I am having a data frame as below:我有一个数据框如下:
I need to create a new column, with the name Value-2: if the value-1 is less than 500, you need to fill the value with 0.5.我需要创建一个新列,名称为 Value-2:如果 value-1 小于 500,则需要用 0.5 填充该值。 if the value is less than 1000, you need to fill the value with 1.如果该值小于1000,则需要用1填充该值。
Expected Result:预期结果:
Can someone help me?有人能帮我吗?
I think np.where function will work efficiently on huge data as well.我认为 np.where function 也能有效处理海量数据。
import pandas as pd
import numpy as np
dictionary = {
"Company" : ['A','A','A','A','A','A'],
"Value1" : [480,120,876,340,996,1104]
}
dataframe = pd.DataFrame(dictionary)
dataframe["Value2"] = np.where(dataframe["Value1"] < 500, 1, 0.5)
Output: Output:
Company Value1 Value2
0 A 480 0.5
1 A 120 0.5
2 A 876 1.0
3 A 340 0.5
4 A 996 1.0
5 A 1104 1.0
Try this you can adapt the algorithm according to your needs.试试这个你可以根据你的需要调整算法。 Here is a simple if
/ else
.这是一个简单的if
/ else
。
df['Value-2'] = df['Value-1'].apply(lambda x: 0.5 if x < 500 else 1)
# Company Value-1 Value-2
# 0 A 480 0.5
# 1 A 120 0.5
# 2 A 876 1.0
# 3 A 340 0.5
# 4 A 996 1.0
# 5 A 1104 1.0
As requested here is how to write a custom function to have more flexibility than a one-liner lambda function.这里要求的是如何编写自定义 function 比单行 lambda function 具有更大的灵活性。
def my_fun(x):
# can be a switch case or any complex algorithm
return 0.5 if x < 500 else 1
df['Value-2'] = df['Value-1'].apply(my_fun)
The question is not consistent on one point.这个问题在一点上并不一致。 It says它说
if value is less than 1000, need to fill the value with 1.如果值小于 1000,需要用 1 填充值。
But the expected result shows a Value-2 = 1
for a "Value-1" higher than 1000: Value-1 = 1104
.但是对于高于 1000 的“Value-1”,预期结果显示Value-2 = 1
: Value-1 = 1104
。
Please provide a working code in the future when asking questions.请日后提问时提供工作代码。
import pandas as pd
Data = {
"Company" : ['A','A','A','A','A','A'],
"Value1" : [480,120,876,340,996,1104]
}
DataFrame1 = pd.DataFrame(Data)
DataFrame2 = []
for x in DataFrame1['Value1']:
if x < 500 : DataFrame2.append(0.5)
elif x < 1000 or x > 1000 : DataFrame2.append(1) # As the picture given in the question tells Value 2 is 1 when value 1 is 1104
else : pass
DataFrame1['Value2'] = DataFrame2
print(DataFrame1)
Outputs
Company Value1 Value2
0 A 480 0.5
1 A 120 0.5
2 A 876 1.0
3 A 340 0.5
4 A 996 1.0
5 A 1104 1.0
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