从 TXT 文件中提取逻辑条件并将其应用于 R 中的数据

Question

I am trying to use R to extract some operational condition (ie X>10) found in txt file and apply them to attached data in R. So, I attached a data to R in csv format of row=40 and column=4 (X1,X2,X3,X4).

dat1=readLines("Patterns Interpreted.txt")
dat1
 [1] "-------------------------" "  Class 1 Vs. Class 0"     "-------------------------"
 [4] "Pattern  1"                "X4  Less Than  141.5"      ""                         
 [7] "-------------------------" "  Class 0 Vs. Class 1"     "-------------------------"
[10] "Pattern  1"                "X4  Greater Than   141.5"  ""                         

dat2<-read.csv("LR.csv")
dat2
     X1    X2    X3  X4   X5  X6    Y
1  2140 20640 30250 205 1732  99 4540
2  2016 20280 30010 195 1697 100 4315
3  1905 19860 29780 184 1662  97 4095

# For replacement in txt file
tx2  <- gsub(pattern = "  Less Than  ", replace = "<", x = dat1)
tx22 <- gsub(pattern = "  Greater Than   ", replace = ">", x = tx2)
tx22
 [1] "-------------------------" "  Class 1 Vs. Class 0"     "-------------------------"
 [4] "Pattern  1"                "X4<141.5"                  ""                         
 [7] "-------------------------" "  Class 0 Vs. Class 1"     "-------------------------"
[10] "Pattern  1"                "X4>141.5"                  ""         

Refer to txt there is condition for each pattern. I need to extract these conditions automatically as logical conditions. In other words, if I have X4=120 which satisfy the first condition let say a new variable p=0 while does not satisfy the second condition so p=1 .

How to do this in R?

Answer 1

You can use eval with str2lang to succeed that.

x<-5
str_cond<-"x<3"
condition<-str2lang(str_cond)
eval(condition) #prints FALSE

For your example split your string condition to right and left part and use the left part as string index name to your dat1 to get the column you want.

str_cond<-"X4<141.5"
cond_parts<-strplit(str_cond,"<")[[1]] # split string
assign(cond_parts[1],dat1[,cond_parts[1]]) # create variable with name the left part and assign the column
condition<-str2lang(str_cond) # create language condition
eval(condition) # execute the language condition