python print

https://blog.csdn.net/funnyPython/article/details/78141649

TypeError: sequence item 0: expected str instance, int found

小例子：

a = ['1','2','3',1]
print(' '.join(a))

以为会打印 1 2 3 1 
结果报了错

Traceback (most recent call last):
  File "C:/Users/Administrator/Desktop/onetest.py", line 188, in <module>
    print(' '.join(a))
TypeError: sequence item 3: expected str instance, int found

上网查了资料，说list包含数字，不能直接转化成字符串。 
解决办法：

print(" ".join('%s' %id for id in list1))

即遍历list的元素，把他转化成字符串。这样就能成功输出1 2 3 1了。