Re: [R] creating a new column thanks for the help But l ened up using    act.surv.time<-pmin(m[,"censoringTime"],m[,"survivalTime"])    m<-cbind(m,act.surv.time) which seems to work thanks    "Schmitt, Corinna"  wrote:  Hallo, I just tried, if my solution might be possible for you. Here is the result: > s=2 >        while(s!=0){ n=20 +          m<-matrix(nrow=n,ncol=4) +          colnames(m)=c("treatmentgrp","strata","censoringTime","survivalTime") +         for(i in 1:20)  m[i,]<-c(sample(c(1,2),1,replace=TRUE),sample(c(1,2),1,replace=TRUE),rexp(1,.007),rexp(1,.002)) +         m<-cbind(m,0) +          m[m[,3]>m[,4],5]<-1 +          colnames(m)[5]<-"censoring" +       print(m) +        s=s-1 + } #bilding a data frame from m x=data.frame(m) # adding a column, where nrow(x) = number of row in x and in the  # new coulmn should stand the entries 1...20. x=data.frame(x,"actual surv time"=c(1:nrow(x))) > x    treatmentgrp strata censoringTime survivalTime censoring actual.surv.time 1             1      2    377.486125   1070.66287         0                1 2             1      2    242.468604   1061.30474         0                2 3             1      2     40.904656     51.88263         0                3 4             2      2     44.025595    590.15317         0                4 5             1      1    253.093279    247.32141         1                5 6             2      2     50.486272    257.25016         0                6 7             1      1    337.591250    554.05931         0                7 8             2      2     74.905075    873.14563         0                8 9             1      2     57.196581    765.43142         0                9 10            1      2    370.147307   1646.65368         0               10 11            1      2    152.738532    480.12355         0               11 12            2      2     15.313303    139.19791         0               12 13            1      2     17.205624    641.15764         0               13 14            2      1     81.753924    107.02202         0               14 15            1      2     60.774221    665.27500         0               15 16            2      1      8.712562    142.90775         0               16 17            1      1     54.542722   1904.88060         0               17 18            2      2     85.626140    214.66811         0               18 19            2      1     31.257923    739.96591         0               19 20            1      1     85.910141    306.14860         0               20 See it works! For more information of data frames, see ?data.frame  Here are some additional examples. > x[2,6]  # Extraction of special entries: x[2,6]= 2 -> row 2, column 6 [1] 2 > x[2,6]=100  # Changing entires: x[2,6]=100 > x    treatmentgrp strata censoringTime survivalTime censoring actual.surv.time 1             1      2    377.486125   1070.66287         0                1 2             1      2    242.468604   1061.30474         0              100 3             1      2     40.904656     51.88263         0                3 4             2      2     44.025595    590.15317         0                4 5             1      1    253.093279    247.32141         1                5 6             2      2     50.486272    257.25016         0                6 7             1      1    337.591250    554.05931         0                7 8             2      2     74.905075    873.14563         0                8 9             1      2     57.196581    765.43142         0                9 10            1      2    370.147307   1646.65368         0               10 11            1      2    152.738532    480.12355         0               11 12            2      2     15.313303    139.19791         0               12 13            1      2     17.205624    641.15764         0               13 14            2      1     81.753924    107.02202         0               14 15            1      2     60.774221    665.27500         0               15 16            2      1      8.712562    142.90775         0               16 17            1      1     54.542722   1904.88060         0               17 18            2      2     85.626140    214.66811         0               18 19            2      1     31.257923    739.96591         0               19 20            1      1     85.910141    306.14860         0               20 > t=x > row2=t[-2,] # deleting a row > row2    treatmentgrp strata censoringTime survivalTime censoring actual.surv.time 1             1      2    377.486125   1070.66287         0                1 3             1      2     40.904656     51.88263         0                3 4             2      2     44.025595    590.15317         0                4 5             1      1    253.093279    247.32141         1                5 6             2      2     50.486272    257.25016         0                6 7             1      1    337.591250    554.05931         0                7 8             2      2     74.905075    873.14563         0                8 9             1      2     57.196581    765.43142         0                9 10            1      2    370.147307   1646.65368         0               10 11            1      2    152.738532    480.12355         0               11 12            2      2     15.313303    139.19791         0               12 13            1      2     17.205624    641.15764         0               13 14            2      1     81.753924    107.02202         0               14 15            1      2     60.774221    665.27500         0               15 16            2      1      8.712562    142.90775         0               16 17            1      1     54.542722   1904.88060         0               17 18            2      2     85.626140    214.66811         0               18 19            2      1     31.257923    739.96591         0               19 20            1      1     85.910141    306.14860         0               20 > column3=t[,-3] # deleting a column > column3    treatmentgrp strata survivalTime censoring actual.surv.time 1             1      2   1070.66287         0                1 2             1      2   1061.30474         0              100 3             1      2     51.88263         0                3 4             2      2    590.15317         0                4 5             1      1    247.32141         1                5 6             2      2    257.25016         0                6 7             1      1    554.05931         0                7 8             2      2    873.14563         0                8 9             1      2    765.43142         0                9 10            1      2   1646.65368         0               10 11            1      2    480.12355         0               11 12            2      2    139.19791         0               12 13            1      2    641.15764         0               13 14            2      1    107.02202         0               14 15            1      2    665.27500         0               15 16            2      1    142.90775         0               16 17            1      1   1904.88060         0               17 18            2      2    214.66811         0               18 19            2      1    739.96591         0               19 20            1      1    306.14860         0               20 Happy working, Corinna -----Ursprï¿½ngliche Nachricht----- Von: r-help-bounces@stat.math.ethz.ch [mailto:r-help-bounces@stat.math.ethz.ch] Im Auftrag von Schmitt, Corinna Gesendet: Dienstag, 8. Mai 2007 10:06 An: raymond chiruka; r Betreff: Re: [R] creating a new column Hallo, I  just now a solution for da data frame. I'm not sure if this is what you  want. Just try if it helps. Here an example of my code where I added a  column: df <- rbind( c("fred","mary",4),c("fred","mary",7),              c("fred","mary",9),c("barney","liz",3),              c("barney","liz",5)) df <- data.frame(df) colnames(df) <- c("father","mother","child.age") # adding column df <- data.frame(df,"weddingdate"=c("Dec 12th, 1980","Dec 12th, 1980",                                     "Dec 12th, 1980","Apr 9th, 2003",                                       "Apr 9th, 2003")) df        The R-Gui Result:   father mother child.age    weddingdate 1   fred   mary         4 Dec 12th, 1980 2   fred   mary         7 Dec 12th, 1980 3   fred   mary         9 Dec 12th, 1980 4 barney    liz         3  Apr 9th, 2003 5 barney    liz         5  Apr 9th, 2003 Caution: the number of entries in adding column must correspond to the number of rows in your existing data frame df (here 5) Try this soultion, Corinna -----Ursprï¿½ngliche Nachricht----- Von: r-help-bounces@stat.math.ethz.ch [mailto:r-help-bounces@stat.math.ethz.ch] Im Auftrag von raymond chiruka Gesendet: Montag, 7. Mai 2007 16:28 An: r Betreff: [R] creating a new column hie l would like to create a 6th column "actual surv time" from the following data       the condition being   if  censoringTime>survivaltime then actual survtime =survival time   else actual survtime =censoring time      the code l used to create the data is           s=2        while(s!=0){ n=20          m<-matrix(nrow=n,ncol=4)          colnames(m)=c("treatmentgrp","strata","censoringTime","survivalTime")         for(i in 1:20)  m[i,]<-c(sample(c(1,2),1,replace=TRUE),sample(c(1,2),1,replace=TRUE),rexp(1,.007),rexp(1,.002))         m<-cbind(m,0)          m[m[,3]>m[,4],5]<-1          colnames(m)[5]<-"censoring"       print(m)        s=s-1           treatmentgrp strata censoringTime survivalTime censoring    [1,]             1      1       1.012159    1137.80922         0    [2,]             2      2      32.971439     247.21786         0    [3,]             2      1      85.758253     797.04949         0    [4,]             1      1      16.999171      78.92309         0    [5,]             2      1     272.909896     298.21483         0    [6,]             1      2     138.230629     935.96765         0    [7,]             2      2      91.529859     141.08405         0         l keep getting an error message when i try to  create the 6th column                      ---------------------------------  [[alternative HTML version deleted]] ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.         --------------------------------- 	[[alternative HTML version deleted]]