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MathGroup Archive 1998

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Re: List handling

  • To: mathgroup at smc.vnet.net
  • Subject: [mg15284] Re: List handling
  • From: dreissBLOOP at bloop.earthlink.net (David Reiss)
  • Date: Thu, 31 Dec 1998 04:39:38 -0500
  • Organization: EarthLink Network, Inc.
  • References: <76ciqj$o51@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

In article <76ciqj$o51 at smc.vnet.net>, "Jorge Zickermann"
<jzickermann at mail.EUnet.pt> wrote:

> listA= 
> 
> {1977.06,1977.06,1977.06,1977.06,1977.06,2047.77,2047.77,2047.77,2047.77,218
> 1.55,2181.55,2181.55,2244.73,2244.73,2244.73,2305.5,2305.5,2305.5,2305.5,236
> 3.92,2363.92,2363.92,2363.92,2363.92,2363.92,2363.92,2363.92,2363.92,2363.92
> ,2363.92}
> 
> ListB= 
> 
> {0.684807,0.683029,0.665242,0.665242,0.664123,0.683029,0.665242,0.665242,0.6
> 64123,0.640339,0.640339,0.620329,0.640339,0.640339,0.620329,0.661684,0.64033
> 9,0.640339,0.620329,0.640339,0.622044,0.640339,0.621506,0.660996,0.640339,0.
> 641006,0.640339,0.620935,0.640339,0.640339}
> 
> ListC=
> 
> {1971.45,1973.53,1994.29,1994.29,1995.6,2044.23,2065.,2065.,2066.3,2227.86,2
> 227.86,2251.22,2291.04,2291.04,2314.4,2326.89,2351.81,2351.81,2375.17,2410.2
> 2,2431.58,2410.22,2432.21,2386.11,2410.22,2409.44,2410.22,2432.88,2410.22,24
> 10.22}
> 
> Position[ListB,_?(#>0.68&)]
> 
> {{1},{2},{6}}
> 
> Having obtained the positions of certain selected elements from ListB, I
> want to substitute the corresponding elements in ListA by the
> corresponding elements in ListC. In other words, I want to end up with;
> 
> 
> listA= 
> 
> {1971.45,1973.53,1977.06,1977.06,1977.06,2044.23,2047.77,2047.77,2047.77,218
> 1.55,2181.55,2181.55,2244.73,2244.73,2244.73,2305.5,2305.5,2305.5,2305.5,236
> 3.92,2363.92,2363.92,2363.92,2363.92,2363.92,2363.92,2363.92,2363.92,2363.92
> ,2363.92}
> 
> Any help on how to do this is welcome. Thank you.
> 
>     Jorge


In[1]:=
ListA={1977.06,1977.06,1977.06,1977.06,1977.06,2047.77,
      2047.77,2047.77,2047.77,2181.55,2181.55,2181.55,2244.73,
      2244.73,2244.73,2305.5,2305.5,2305.5,2305.5,2363.92,2363.92,
     
2363.92,2363.92,2363.92,2363.92,2363.92,2363.92,2363.92,2363.92,2363.92};

In[2]:=
ListB={0.684807,0.683029,0.665242,0.665242,0.664123,
      0.683029,0.665242,0.665242,0.664123,0.640339,0.640339,
      0.620329,0.640339,0.640339,0.620329,0.661684,0.640339,
      0.640339,0.620329,0.640339,0.622044,0.640339,0.621506,
      0.660996,0.640339,0. 641006,0.640339,0.620935,0.640339,0.640339};

In[3]:=
ListC={1971.45,1973.53,1994.29,1994.29,1995.6,2044.23,
      2065.,2065.,2066.3,2227.86,2227.86,2251.22,2291.04,
      2291.04,2314.4,2326.89,2351.81,2351.81,2375.17,2410.22,
      2431.58,2410.22,2432.21,2386.11,2410.22,2409.44,2410.22,
      2432.88,2410.22,2410.22};

In[4]:= pos=Position[ListB,_?(#>0.68&)]

Out[4]=
{{1},{2},{6}}


ReplacePart has a syntax that should do exactly what you want. 
Unfortunately there is a bug in Mathematica 3 that prevents it from
evaluating according to expectations (it appears that this syntax was
not implemented as advertised, but it works in the upcoming version)


In[5]:= ReplacePart[ListA,ListC,pos,pos]

Out[5]=
{{1971.45,1973.53,1994.29,1994.29,1995.6,2044.23,2065.,2065.,2066.3,2227.86,
     
2227.86,2251.22,2291.04,2291.04,2314.4,2326.89,2351.81,2351.81,2375.17,
     
2410.22,2431.58,2410.22,2432.21,2386.11,2410.22,2409.44,2410.22,2432.88,
     
2410.22,2410.22}\[LeftDoubleBracket]{1},{2},{6}\[RightDoubleBracket],{
      1971.45,1973.53,1994.29,1994.29,1995.6,2044.23,2065.,2065.,2066.3,
     
2227.86,2227.86,2251.22,2291.04,2291.04,2314.4,2326.89,2351.81,2351.81,
     
2375.17,2410.22,2431.58,2410.22,2432.21,2386.11,2410.22,2409.44,2410.22,
      2432.88,2410.22,2410.22}\[LeftDoubleBracket]{1},{2},{6}
      \[RightDoubleBracket],1977.06,1977.06,
 
1977.06,{1971.45,1973.53,1994.29,1994.29,1995.6,2044.23,2065.,2065.,2066.3,
     
2227.86,2227.86,2251.22,2291.04,2291.04,2314.4,2326.89,2351.81,2351.81,
     
2375.17,2410.22,2431.58,2410.22,2432.21,2386.11,2410.22,2409.44,2410.22,
      2432.88,2410.22,2410.22}\[LeftDoubleBracket]{1},{2},{6}
     
\[RightDoubleBracket],2047.77,2047.77,2047.77,2181.55,2181.55,2181.55,
 
2244.73,2244.73,2244.73,2305.5,2305.5,2305.5,2305.5,2363.92,2363.92,2363.92,
  2363.92,2363.92,2363.92,2363.92,2363.92,2363.92,2363.92,2363.92}


However, the following should do what you want


In[6]:=
testListA=ReplacePart[ListA, 0, pos]+(ListC-ReplacePart[ListC, 0, pos])

Out[6]=
{1971.45,1973.53,1977.06,1977.06,1977.06,2044.23,2047.77,2047.77,2047.77,
 
2181.55,2181.55,2181.55,2244.73,2244.73,2244.73,2305.5,2305.5,2305.5,2305.5,
 
2363.92,2363.92,2363.92,2363.92,2363.92,2363.92,2363.92,2363.92,2363.92,
  2363.92,2363.92}

These are the orignal elements of ListA


In[7]:= ListA[[Flatten[pos]]]

Out[7]=
{1977.06,1977.06,2047.77}

These are the elements of ListC that you are interested in placing in
ListA


In[8]:= ListC[[Flatten[pos]]]

Out[8]=
{1971.45,1973.53,2044.23}

And here they have been put into the new testListA


In[9]:= testListA[[Flatten[pos]]]

Out[9]=
{1971.45,1973.53,2044.23}


testListA only differs from ListA at the positions in question


In[10]:= testListA-ListA

Out[10]=
{-5.61,-3.53,0.,0.,0.,-3.54,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,0.,
  0.,0.,0.,0.,0.,0.,0.,0.}


Cheers,


David

-- 
David Reiss
dreissBLOOP at bloop.earthlink.net
To send personal email, remove the words  "bloop" and "BLOOP" from the
email address


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