Hi¡ I have a doubt and I hope someone can help me please, I have a dataframe in R and it makes a double cicle for and an if, the data frame has some values and then if the condition is True, it makes some operations, the problem is I can't understand neither the cicle and the operation the code makes under the condition.
I reply the code I have in a simpler one but the idea is the same. And if someone can explain me the whole operation please.
w<-c(2,5,4,3,5,6,8,2,4,6,8)
x<-c(2,5,6,7,1,1,4,9,8,8,2)
y<-c(2,5,6,3,2,4,5,6,7,3,5)
z<-c(2,5,4,5,6,3,2,5,6,4,6)
letras<-data.frame(w,x,y,z)
l=1
o=1
v=nrow(letras)
letras$op1<-c(1)
letras$op2<-c(0)
for (l in 1:v) {
for (o in 1:v) {
if(letras$x[o]==letras$y[l] & letras$z[l]==letras$z[o] & letras$w[l]){
letras$op1<-letras$op1+1
letras$op2<-letras$x*letras$y
}
}
}
The result is the following:
Thanks¡¡¡¡¡
This segment of code is storing values into vectors labeled w,x,y,z.
w<-c(2,5,4,3,5,6,8,2,4,6,8)
x<-c(2,5,6,7,1,1,4,9,8,8,2)
y<-c(2,5,6,3,2,4,5,6,7,3,5)
z<-c(2,5,4,5,6,3,2,5,6,4,6)
It then transforms the 4 vectors into a data frame
letras<-data.frame(w,x,y,z)
This bit of code isn't doing anything as far as I can tell.
l=1 #???
o=1 #???
This counts how many rows is in the letras data frame and stores to v, in this case 11 rows.
v=nrow(letras)
This creates new columns in letras dataframe with all ones in op1 and all zeros in op2
letras$op1<-c(1)
letras$op2<-c(0)
Here each for loop is acting as a counter, and will run the code beneath it iteratively from 1 to v (11), so 11 iterations. Each iteration the value of l will increase by 1. So first iteration l = 1, second l=2... etc.
for (l in 1:v) {
You then have a second counter, which is running within the first counter. So this will iterate over 1 to 11, exactly the same way as above. But the difference is, this counter will need to complete it's 1 to 11 cycle before the top level counter can move onto the next number. So o will effectively cycle from 1 to 11, for each 1 count of 1l. So with the two together, the inside for loop will count from 1 to 11, 11 times.
for (o in 1:v) {
You then have a logical statement which will run the code beneath if the column x and column y values are the same. Remember they will be calling different index values so it could be 1st x value vs the 2nd y value. There is an AND statement so it also needs the two z position values to be equal. and the last part letras$w[l] is always true in this particular example, so could possibly be removed.
if(letras$x[o]==letras$y[l] & letras$z[l]==letras$z[o] & letras$w[l]){
Lastly, is the bit that happens if the above statement is true.
op1 get's 1 added (remember this was starting from 1 anyway), and op2 multiplies x*y columns together. This multiplication is perhaps a little bit inefficient, because x and y do not change, so the answer will calculate the same result each time the the if statement evaluates TRUE.
letras$op1<-letras$op1+1
letras$op2<-letras$x*letras$y
}
}
}
Hope this helps.
I am learning matrix multiplication in R and following is what I want to achieve. I am doing this purely to upscale my skills in R.
Following is the kind of matrix I am working with:
m <- matrix(1, 100, 10)
I have matrix with only element 1 with 100 rows and 10 columns. Now I want to replace for column 1 with 0 from row1 to row10. Then for the second column, I want to replace 1 with zeros from row 11 to row 20. Similarly for for the third column, I want to replace 1 with zeros from row 21 to row 30 and similarly for the rest up too column 10. Following my my example
m <- matrix(1, 100, 10)
for(j in 1:10){
for(i in (j-1)*10+1: j*10){
m[i,j] <-0
}
}
I was quite confident that my logic was correct but every time I run my code, I get following error message Subscripts out of bounds Call. I tried couple days now and I could not resolve this problem. I would highly appreciate for any hints or direct solutions to fix this. Many thanks in advance.
You could use just one variable, which I think would be easier. For each column, j, get the lower and upper range of row indices and assign as 0.
for(j in 1:10){
row_lower <- (j-1)*10+1
row_upper <- j*10
m[row_lower: row_upper, j] <- 0
}
Returns 0's in your specified range.
cv.uk.df$new.d[2:nrow(cv.uk.df)] <- tail(cv.uk.df$deaths, -1) - head(cv.uk.df$deaths, -1) # this line of code works
I wanted to know why do we -1 in the tail and -1 in head to create this new column.
I made an effort to understand by removing the -1 and "R"(The code is in R studio) throws me this error.
Could anyone shed some light on this? I can't explain how much I would appreciate it.
Look at what is being done. On the left-hand side of the assignment operator, we have:
cv.uk.df$new.d[2:nrow(cv.uk.df)] <-
Let's pick this apart.
cv.uk.df # This is the data.frame
$new.d # a new column to assign or a column to reassign
[2:nrow(cv.uk.df)] # the rows which we are going to assign
Specifically, this line of code will assign a new value all rows of this column except the first. Why would we want to do that? We don't have your data, but from your example, it looks like you want to calculate the change from one line to the next. That calculation is invalid for the first row (no previous row).
Now let's look at the right-hand side.
<- tail(cv.uk.df$deaths, -1) - head(cv.uk.df$deaths, -1)
The cv.uk.df$deaths column has the same number of rows as the data.frame. R gets grouchy when the numbers of elements don't follow sum rules. For data.frames, the right-hand side needs to have the same number of elements, or a number that can be recycled a whole-number of times. For example, if you have 10 rows, you need to have a replacement of 10 values. Or you can have 5 values that R will recycle.
If your data.frame has 100 rows, only 99 are being replaced in this operation. You cannot feed 100 values into an operation that expects 99. We need to trim the data. Let's look at what is happening. The tail() function has the usage tail(x, n), where it returns the last n values of x. If n is a negative integer, tail() returns all values but the first n. The head() function works similarly.
tail(cv.uk.df$deaths, -1) # This returns all values but the first
head(cv.uk.df$deaths, -1) # This returns all values but the last
This makes sense for your calculation. You cannot subtract the number of deaths in the row before the first row from the number in the first row, nor can you subtract the number of deaths in the last row from the number in the row after the last row. There are more intuitive ways to do this thing using functions from other packages, but this gets the job done.
I need to conditionally replace rows in a data frame (x) with rows selected at random from another data frame (y).Some of the rows between the two data frames are the same and so data frame x will contain rows with repeated information. What sort of base r code would I need to achieve this?
I am writing an agent based model in r where rows can be thought of as vectors of attributes pertaining to an agent and columns are attribute types. For agents to transmit their attributes they need to send rows from one data frame (population) to another, but according to conditional learning rules. These rules need to be: conditionally replace values in row n in data frame x if attribute in column 10 for that row is value 1 or more and if probability s is greater than a randomly selected number between 0 and 1. Probability s is itself an adjustable parameter that can take any value from 0 to 1.
I have tried IF function in the code below, but I am new to r and have made a mistake somewhere with it as I get this warning:
"missing value where TRUE/FALSE needed"
I reckon that I have not specified what should happen to a row if the conditions are not satisfied.
I cannot think of an alternative method of achieving my aim.
Note: agent.dat is data frame x and top_ten_percent is data frame y.
s = 0.7
N = nrow(agent.dat)
copy <- runif(N) #to generate a random probability for each row in agent.dat
for (i in 1:nrow(agent.dat)){
if(agent.dat[,10] >= 1 & copy < s){
agent.dat <- top_ten_percent[sample(nrow(top_ten_percent), 1), ]
}
}
The agent.dat data frame should have rows that are replaced with values from rows in the top_ten_percent data frame if the randomly selected value of copy between 0 and 1 for that row is less than the value of parameter s and if the value for that row in column 10 is 1 or more. For each row I need to replace the first 10 columns of agent.dat with the first 10 columns of top_ten_percent (excluding column 11 i.e. copy value).
Assistance with this problem is greatly appreciated.
So you just need to change a few things.
You need to get a particular value for copy for each iteration of the for loop (use: copy[i]).
You also need to make the & in the if statement an && (Boolean operators && and ||)
Then you need to replace a particular row (and columns 1 through 10) in agent.dat, instead of the whole thing (agent.dat[i,1:10])
So, the final code should look like:
copy <- runif(N)
for (i in 1:nrow(agent.dat)){
if(agent.dat[,10] >= 1 && copy[i] < s){
agent.dat[i,1:10] <- top_ten_percent[sample(nrow(top_ten_percent), 1), ]
}
}
This should fix your errors, assuming your data structure fits your code:
copy <- runif(nrow(agent.dat))
s <- 0.7
for (i in 1:nrow(agent.dat)){
if(agent.dat[i,10] >= 1 & copy[i] < s){
agent.dat[i,] <- top_ten_percent[sample(1:nrow(top_ten_percent), 1), ]
}
}
Here is what I currently Have. I have a column named "test1M", which has values of either 0 or 1. If the value is 1, I want to set the next 20 values in column "test1Mxx" to value 1.
If I run this code, I get an error of (Error in if (data$test1M[x] == 1) { : argument is of length zero).
Whats a better way for me to do this? The code is pretty repetitive, so I would like to minimize that if possible. If there is a way to turn this into a function that would be preferable, so I could change the number of values (for instance, maybe the following 25 values, or 40 values, etc.)
for(x in data$test1){
if(data$test1[x]==1){
data$test2[x+1]=1
data$test2[x+2]=1
data$test2[x+3]=1
data$test2[x+4]=1
data$test2[x+5]=1
data$test2[x+6]=1
data$test2[x+7]=1
data$test2[x+8]=1
data$test2[x+9]=1
data$test2[x+10]=1
data$test2[x+11]=1
data$test2[x+12]=1
data$test2[x+13]=1
data$test2[x+14]=1
data$test2[x+15]=1
data$test2[x+16]=1
data$test2[x+17]=1
data$test2[x+18]=1
data$test2[x+19]=1
data$test2[x+20]=1}
}
Your loop doesn't work because x is a value of data$test1, not an index of it. You need something like:
data$test2 <- data$test1
for (x in seq_along(data$test1))
if (data$test1[x] == 1) data$test2[x + 1:20] <- 1