Re: Re: Replace specific element with specific value.

*To*: mathgroup at smc.vnet.net*Subject*: [mg99732] Re: [mg99679] Re: Replace specific element with specific value.*From*: Bob Hanlon <hanlonr at cox.net>*Date*: Tue, 12 May 2009 03:11:01 -0400 (EDT)*Reply-to*: hanlonr at cox.net

myReplacePart[data_List, pos_List, parts_List] := Module[{newList = data}, ( newList = ReplacePart[newList, #[[1]] -> #[[2]]]) & /@ Transpose[{Thread[{pos, 2}], parts}]; newList] /; Length[pos] == Length[parts] data = {{0, 2}, {2, 3}, {3, 4}, {4, 6}, {6, 8}, {8, 9}, {9, 10}}; positionList = {3, 6, 7}; replacementList = {8, 17, 25}; myReplacePart[data, positionList, replacementList] {{0, 2}, {2, 3}, {3, 8}, {4, 6}, {6, 8}, {8, 17}, {9, 25}} Bob Hanlon ---- nick.maj at mssm.edu wrote: ============= Thank you all for the replies. Bill, you are right. To manually input the replacement rules is fine for only a view variables. For simplicity I kept my example short. However, I am dealing with quite large lists (100+), so a functional/ programatical approach is necessary. Also, I used characters for clarity. Rule @@@ (ToExpression[{#, # <> "+" <> # <> #}] & /@ {"1", "2", "3"}) gives: {1 -> 12, 2 -> 24, 3 -> 36} Let me elaborate on this problem again with numbers only. data = {{0, 2}, {2, 3}, {3, 4}, {4, 6}, {6, 8}, {8, 9}, {9, 10}} positionList = {3, 6, 7} replacementList = {8, 17, 25} needed output: {{0, 2}, {2, 3}, {3, 8}, {4, 6}, {6, 8}, {8, 17}, {9, 25}} Based on the positionList - replacementList information, the function must replace the 2nd element in the 3rd, 6th and 7th list of data with the value 8, 17 and 25 respectively. I experimented with MapThread[ReplacePart ... but without success. Thanks in advance, Nick.