I want to define a function to which the input parameters can be omitted or have a default value.
I have this function:
def nearxy(x,y,x0,y0,z):
distance=[]
for i in range(0,len(x)):
distance.append(abs(math.sqrt((x[i]-x0)**2+(y[i]-y0)**2)))
...
return min(distance)
I want make x0 and y0 have a default value, and make z optional if I don't have a z value.
How can I do that? Thank you.
You can't make function arguments optional in Python, but you can give them default values. So:
def nearxy(x, y, x0=0, y0=0, z=None):
...
That makes x0 and y0 have default values of 0, and z have a default value of None.
Assuming None makes no sense as an actual value for z, you can then add logic in the function to do something with z only if it's not None.
None as a default argument makes sense cause the default argument object is persistent between calls of the function. See stackoverflow.com/questions/1132941/…def nearxy(x, y, x0 = 0, y0 = 0, z = None):
...
Check if z is None to see if it has been omitted.
give default values to x0,y0 like this and if z is optional also :
def nearxy(x,y,x0=0,y0=0,z=None):
distance=[]
for i in range(0,len(x)):
distance.append(abs(math.sqrt((x[i]-x0)**2+(y[i]-y0)**2)))
if z is not None:
blah blah
return min(distance)
call :
nearxy(1,2)
if you want only toassign z :
nearxy(1,2,z=3)
....
hope this helps
To specify a default value, define the parameter with a '=' and then the value.
An argument where a default value is specified is an optional argument.
For example, if you wanted x0,y0, and z to have default values of 1,2,3:
def nearxy(x,y,x0=1,y0=2,z=3):
distance=[]
for i in range(0,len(x)):
distance.append(abs(math.sqrt((x[i]-x0)**2+(y[i]-y0)**2)))
...
return min(distance)
See http://docs.python.org/2/tutorial/controlflow.html#default-argument-values for more.
