python 关于用for打印图案

如何用 for循环语句以#打印一个正弦图像
Modify the following program to ask the user for the number of steps (instead of using 31 fixed steps).
import math

sin = math.sin
pi = math.pi

for i in range(31):
x = float(i) / 30.0 * 2 * pi
print( sin(x) )

 #!/usr/bin/python
# -*- coding: UTF-8 -*-
import math
def pr(i):
    #输出##
    if i>0:
        i=i*2
    elif i<0:
        i*=-1;
    str=""
    while i>0:
        str+="#";
        i-=1;
    print str;

sin = math.sin
pi = math.pi
for i in range(31):
  x = float(i) / 30.0 * 2 * pi
  y=sin(x)*20
  pr(y)

上面的哪个代码，if判断多此一举。。

 #!/usr/bin/python
# -*- coding: UTF-8 -*-
import math
def pr(i):
    #输出##
    str=""
    while i>0:
        str+="#";
        i-=1;
    print str;

sin = math.sin
pi = math.pi
for i in range(31):
  x = float(i) / 30.0 * 2 * pi
  y=sin(x)*20
  pr(y)