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Replace each value in a column with the largest value based on a condition in R data frame.
Suppose we have three columns say X, Y, and Z in an R data frame called df and we want to replace values in columns X and Y with the same value if the values are greater than values in Z and if they are less than the values in Z then we can replace with Z values.
Check out the below Examples to understand how it can be done.
Example 1
Following snippet creates a sample data frame −
x1<-rpois(20,2) x2<-rpois(20,2) X<-rpois(20,3) df1<-data.frame(x1,x2,X) df1
The following dataframe is created
x1 x2 X 1 1 1 3 2 2 2 2 3 1 0 2 4 2 4 0 5 3 3 4 6 4 1 1 7 1 3 2 8 4 2 2 9 4 3 3 10 0 0 2 11 1 4 4 12 2 2 3 13 2 2 1 14 2 1 1 15 3 2 4 16 0 5 1 17 0 0 2 18 1 1 5 19 1 1 3 20 4 2 2
To replace values in x1 and x2 with X if they are less than X on the above created data frame, add the following code to the above snippet −
x1<-rpois(20,2) x2<-rpois(20,2) X<-rpois(20,3) df1<-data.frame(x1,x2,X) df1[,1:2]<-lapply(df1[,1:2],function(x) ifelse(xdf1$X,x,X)) df1
Output
If you execute all the above given snippets as a single program, it generates the following Output −
x1 x2 X 1 3 3 3 2 2 2 2 3 2 2 2 4 2 4 0 5 4 4 4 6 4 1 1 7 2 3 2 8 4 2 2 9 4 3 3 10 2 2 2 11 4 4 4 12 3 3 3 13 2 2 1 14 2 1 1 15 4 4 4 16 1 5 1 17 2 2 2 18 5 5 5 19 3 3 3 20 4 2 2
Example 2
Following snippet creates a sample data frame −
y1<-rnorm(20,0.5) y2<-rnorm(20,0.5) Y<-rnorm(20,0.5,0.005) df2<-data.frame(y1,y2,Y) df2
The following dataframe is created
y1 y2 Y 1 0.38903537 2.2068051 0.5082834 2 0.08703056 1.4083968 0.5056107 3 0.37278616 1.1038885 0.4990037 4 0.80350925 1.9704348 0.5038784 5 0.97611860 1.2431881 0.5008880 6 -0.61610694 0.7217463 0.4940775 7 -0.37572148 2.6484561 0.5016710 8 1.61492508 -0.8688714 0.5046321 9 0.58858684 -0.7627633 0.5020626 10 2.45589388 0.5280574 0.4963291 11 0.79954296 0.3476735 0.4998230 12 0.32497257 -1.1904892 0.4979471 13 -1.00420011 -1.4069050 0.5007824 14 3.57048593 1.2896375 0.4987264 15 2.26500575 1.5387301 0.5037580 16 1.58224909 -0.9105896 0.4838976 17 -0.31704488 -0.1611695 0.4917168 18 0.89396005 -1.0374997 0.4976947 19 -0.18188955 0.2133147 0.4915311 20 1.27196146 -0.7174173 0.4922855
To replace values in y1 and y2 with Y if they are less than Y on the above created data frame, add the following code to the above snippet −
y1<-rnorm(20,0.5) y2<-rnorm(20,0.5) Y<-rnorm(20,0.5,0.005) df2<-data.frame(y1,y2,Y) df2[,1:2]<-lapply(df2[,1:2],function(x) ifelse(xdf2$Y,x,Y)) df2
Output
If you execute all the above given snippets as a single program, it generates the following Output −
y1 y2 Y 1 0.5082834 2.2068051 0.5082834 2 0.5056107 1.4083968 0.5056107 3 0.4990037 1.1038885 0.4990037 4 0.8035093 1.9704348 0.5038784 5 0.9761186 1.2431881 0.5008880 6 0.4940775 0.7217463 0.4940775 7 0.5016710 2.6484561 0.5016710 8 1.6149251 0.5046321 0.5046321 9 0.5885868 0.5020626 0.5020626 10 2.4558939 0.5280574 0.4963291 11 0.7995430 0.4998230 0.4998230 12 0.4979471 0.4979471 0.4979471 13 0.5007824 0.5007824 0.5007824 14 3.5704859 1.2896375 0.4987264 15 2.2650058 1.5387301 0.5037580 16 1.5822491 0.4838976 0.4838976 17 0.4917168 0.4917168 0.4917168 18 0.8939600 0.4976947 0.4976947 19 0.4915311 0.4915311 0.4915311 20 1.2719615 0.4922855 0.4922855
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