Comparing strings in R
I have the following data frame,
R_Number A
1 0
2 15
3 10
4 11
5 12
6 18
7 19
8 15
9 17
10 11
Now I need to create another column B
where the comparison of values in A
. The condition is that the comparison is not between two consecutive strings , i.e. Row number 1
is compared to Row number 4
, as wise is Row number 2
compared to Row number 5
, and this iteration continues until the end of the data. Comparison condition:
if (A[1]>=15 && A[4] <= 12) {
B == 1
}
else if (A[1]<=0 && A[4]>= 10) {
B== 2
}
else {
B== 0
}
When it comes to Row number 8 and Row number 9
, these lines will not compare the next fourth line, so the value should be0
In addition, the comparison result is Row 1 and 4
printed in Row number 1
, similarly the comparison result Row 2 and 5
is printed inRow number 2
Thus, the resulting framework should be as shown below.
R_Number A B
1 0 2
2 15 1
3 10 0
4 11 0
5 12 0
6 18 0
7 19 1
8 15 0
9 17 0
10 11 0
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The variable is delayed first, and then your new variable is evaluated. Something like that:
library(Hmisc)
df <- data.frame(R_Number = c(1:10), A = c(0,15,10,11,12,18,19,15,17,11))
A_Lag<-Lag(df$A,-3)
df$B <- rowSums(cbind(df$A>=15 & A_Lag <= 12,(df$A<=0 & A_Lag>= 10)*2),na.rm= T)
df$B
I tried to avoid operators if
. The function Lag
can be found in the package Hmisc
.
> df$B
[1] 2 1 0 0 0 0 1 0 0 0
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As per @nicola's comment, I tried to solve your problem. I recreated your original dataframe:
df <- data.frame(R_Number = c(1:10), A = c(0,15,10,11,12,18,19,15,17,11), B = 0)
So, I used an if statement inside a loop for:
for (i in 1:(length(df$A)-3)) {
if (df$A[i] >= 15 && df$A[i+3] <= 12) {
df$B[i] <- 1
} else if ((df$A[i] <= 0) && (df$A[i+3] >= 10)) {
df$B[i] <- 2
}
else {
df$B[i] <- 0
}
}
On the last edit, I resolved the issue I had when changing the length of the data frame. You now have a general solution!
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