How to replace values in the columns of a dataframe based on the values in the other column in R?

Question

I have a dataframe containing the safety data for 100 patients. There are different safety factors for each patient with the size of that specific factor.

   v1_d0_urt_redness v1_d0_urt_redness_size v1_d1_urt_redness v1_d1_urt_redness_size ...
P1          1              20             
P2          1              NA
P3          0              NA
.
.
.

Here redness=1 means there was redness and redness=0 means there was no redness, and therefore the redness_size was not reported.
In order to find what proportion of the data is missing I need to code the data as follows: if (the column containing redness=1 & the column containing redness_size=NA) then (the column containing redness_size<-NA) else if (the column containing redness=0 then the column containing redness_size<-0) to have this coded for d0,d1,.. and to repeat this process for the other variables like hardness, swelling and etc. Any ideas how one could implement this in R?

I edited my answer accordingly your resquest. Let me know it works on your dataset — dc37
– dc37, Commented Nov 26, 2019 at 21:38

dc37 · Accepted Answer · 2019-11-27 15:58:24Z

2

If I understand well what you are trying to do and assuming your dataframe is called df, you can change values of the column redness_size by doing this:

df[df[,endsWith(colnames(df),"_redness")] == 1 & is.na(df[,endsWith(colnames(df),"redness_size")]),endsWith(colnames(df),"redness_size")] <- NA
df[df[,endsWith(colnames(df),"_redness")] == 1, endsWith(colnames(df),"redness_size")] <- 0

edited Nov 27, 2019 at 15:58

answered Nov 26, 2019 at 18:03

dc37

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8 Comments

Ecatrina Smith Over a year ago

Thank you, but as there are 5 days for each factor, is there anyway to use the patterns, like if the name contains 'redness' then do this procedure, and it would do it for the variables in 5 days.?

Ecatrina Smith Over a year ago

I am using df[df[,endsWith(colnames(df),"redness")]==0 ,endsWith(colnames(df),"redness_size")]<-0 , but I get the error Error in `[<-.data.frame`(`*tmp*`, df[, endsWith(colnames(df), "redness")] == : non-existent rows not allowed , any ideas what goes wrong here?

Ecatrina Smith Over a year ago

My colnames are :

"v1_d0_urt_redness" "v1_d0_lt_redness"  "v1_d1_urt_redness" "v1_d1_lt_redness"  "v1_d2_urt_redness" "v1_d2_lt_redness" , "v1_d0_urt_redness_size" "v1_d0_lt_redness_size"  "v1_d1_urt_redness_size" "v1_d1_lt_redness_size"  "v1_d2_urt_redness_size"...

, when I am using df[,endsWith(colnames(df),"redness")] I am getting the right columns but the earlier code does not work..

Ecatrina Smith Over a year ago

I edited the question with the updated variable names and checked the summary(df).

dc37 Over a year ago

OK, I modified my answer accordingly. Do you still have the same issue ? Both lines are not working ? Have you check that colnames redness are in numeric format ? You can also try to run only

df[df[,endsWith(colnames(df),"_redness")] == 1 & is.na(df[,endsWith(colnames(df),"redness_size")],endsWith(colnames(df),"redness_size")]

to see what rows have been returned

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