How to sort a data in a column based on specific sample name characters in R?-CodePudding

I have a data frame (in R) that needs to be sorted out by parts of the sample name to do analysis. For example, each sample is coded in this format in a column titled "Sample": 1.4.a.2021 1 is the week 4 is the device number a is the sampling period in the week and 2021 is the year. I want to sort by the "4" (numbers range from 1-12). Can I sort by a particular character in a string--if that is what this is?

CodePudding user response：

It sounds like your data is something like this:

set.seed(1)

df <- data.frame(Sample = paste0("1.", sample(12), ".",sample(letters, 12), "2021"),
                 Data = runif(12))
df
#>        Sample      Data
#> 1   1.9.u2021 0.3823880
#> 2   1.4.j2021 0.8696908
#> 3   1.7.v2021 0.3403490
#> 4   1.1.n2021 0.4820801
#> 5   1.2.y2021 0.5995658
#> 6   1.5.g2021 0.4935413
#> 7   1.3.i2021 0.1862176
#> 8   1.8.o2021 0.8273733
#> 9   1.6.e2021 0.6684667
#> 10 1.11.t2021 0.7942399
#> 11 1.12.q2021 0.1079436
#> 12 1.10.w2021 0.7237109

To sort it we can find the number portion of the string, convert to numeric and order the data frame by it:

df[order(as.numeric(gsub("^.*\\.(\\d )\\..*$", "\\1", df$Sample))),]
#>        Sample      Data
#> 4   1.1.n2021 0.4820801
#> 5   1.2.y2021 0.5995658
#> 7   1.3.i2021 0.1862176
#> 2   1.4.j2021 0.8696908
#> 6   1.5.g2021 0.4935413
#> 9   1.6.e2021 0.6684667
#> 3   1.7.v2021 0.3403490
#> 8   1.8.o2021 0.8273733
#> 1   1.9.u2021 0.3823880
#> 12 1.10.w2021 0.7237109
#> 10 1.11.t2021 0.7942399
#> 11 1.12.q2021 0.1079436

^{Created on 2022-03-20 by the reprex package (v2.0.1)}