使用 Lambda function 打印 python 3

Question

I have the following lists:

para = ['bodyPart', 'shotQuality', 'defPressure', 'numDefPlayers', 'numAttPlayers', 'shotdist', 'angle', 'chanceRating', 'type']

value = [ 0.09786083,  2.30523761, -0.05875112,  
0.07905136, -0.1663424 ,-0.73930942, -0.10385882,  0.98845481,  0.13175622]

I want to print using lambda function.

what i want to show is as follow:

coefficient for 
bodyPart is 0.09786083
shotQuality is 2.30523761
defPressure is -0.05875112
numDefPlayers is 0.07905136 and so on

I use the following code:

b = lambda x:print(para[x],'is',coeff[x])
print('Coefficient for')
print(b)

and it does not work and only shows this:

Coefficient for
<function <lambda> at 0x000001A8A62A0378>

how can i use lambda function to print to show such output.

thanks

Zep

Answer 1

Lambda function is a function, so you need to use parentheses after the function name to actually call it, just like any other function:

for i in range(len(para)):
    print(b(i))

But for the purpose of printing output it's better to use a regular function instead of a lambda function, which is meant for quick expressions rather than functions that do work and return None .

Answer 2

For debugging purposes it can be interesting to print from a lambda function.

You can use a list, tuple or dict to do just that:

Suppose you have lambda function containing a simple test:

lambda x:  x > 10

You can then rewrite to print the incoming variable:

lambda x: [print(x), x > 10][-1]

We can now test:

mylambda = lambda x: [print(x), x > 10][-1]
mylambda(12), mylambda(8)

Which yields:

12
8

(True, False)