Re: strange behavior with Map
- To: mathgroup at smc.vnet.net
- Subject: [mg116401] Re: strange behavior with Map
- From: Bill Rowe <readnews at sbcglobal.net>
- Date: Sun, 13 Feb 2011 03:07:39 -0500 (EST)
On 2/12/11 at 5:20 AM, robertr at math.uh.edu (Robert Rosenbaum) wrote:
>This doesn't seem right:
>In[181]:= Map[Function[x, 2], {{1, 2}, {1, 2}}, 2]
>Out[181]= {2, 2}
>In[180]:= Map[Function[x, 0 x + 2], {{1, 2}, {1, 2}}, 2]
>Out[180]= {{2, 2}, {2, 2}}
What were you expecting? Note
In[52]:= Function[x, 2][{1, 2}]
Out[52]= 2
since this function replaces any argument with 2. But
In[53]:= Function[x, 0 x + 2][{1, 2}]
Out[53]= {2,2}
since this function multiplies the list by 0 then adds 2 which
means the result will have the same number of elements as the
input when the input is a list.
Perhaps you meant to map the function to only level 2 rather
than levels 1 through 2? That is
In[54]:= Map[Function[x, 2], {{1, 2}, {1, 2}}, {2}]
Out[54]= {{2, 2}, {2, 2}}