I have a vector with around 4000 values. I would just need to bin it into 60 equal intervals for which I would then have to calculate the median (for each of the bins).
v<-c(1:4000)
V is really just a vector. I read about cut but that needs me to specify the breakpoints. I just want 60 equal intervals
Use cut and tapply:
> tapply(v, cut(v, 60), median)
(-3,67.7] (67.7,134] (134,201] (201,268]
34.0 101.0 167.5 234.0
(268,334] (334,401] (401,468] (468,534]
301.0 367.5 434.0 501.0
(534,601] (601,668] (668,734] (734,801]
567.5 634.0 701.0 767.5
(801,867] (867,934] (934,1e+03] (1e+03,1.07e+03]
834.0 901.0 967.5 1034.0
(1.07e+03,1.13e+03] (1.13e+03,1.2e+03] (1.2e+03,1.27e+03] (1.27e+03,1.33e+03]
1101.0 1167.5 1234.0 1301.0
(1.33e+03,1.4e+03] (1.4e+03,1.47e+03] (1.47e+03,1.53e+03] (1.53e+03,1.6e+03]
1367.5 1434.0 1500.5 1567.0
(1.6e+03,1.67e+03] (1.67e+03,1.73e+03] (1.73e+03,1.8e+03] (1.8e+03,1.87e+03]
1634.0 1700.5 1767.0 1834.0
(1.87e+03,1.93e+03] (1.93e+03,2e+03] (2e+03,2.07e+03] (2.07e+03,2.13e+03]
1900.5 1967.0 2034.0 2100.5
(2.13e+03,2.2e+03] (2.2e+03,2.27e+03] (2.27e+03,2.33e+03] (2.33e+03,2.4e+03]
2167.0 2234.0 2300.5 2367.0
(2.4e+03,2.47e+03] (2.47e+03,2.53e+03] (2.53e+03,2.6e+03] (2.6e+03,2.67e+03]
2434.0 2500.5 2567.0 2634.0
(2.67e+03,2.73e+03] (2.73e+03,2.8e+03] (2.8e+03,2.87e+03] (2.87e+03,2.93e+03]
2700.5 2767.0 2833.5 2900.0
(2.93e+03,3e+03] (3e+03,3.07e+03] (3.07e+03,3.13e+03] (3.13e+03,3.2e+03]
2967.0 3033.5 3100.0 3167.0
(3.2e+03,3.27e+03] (3.27e+03,3.33e+03] (3.33e+03,3.4e+03] (3.4e+03,3.47e+03]
3233.5 3300.0 3367.0 3433.5
(3.47e+03,3.53e+03] (3.53e+03,3.6e+03] (3.6e+03,3.67e+03] (3.67e+03,3.73e+03]
3500.0 3567.0 3633.5 3700.0
(3.73e+03,3.8e+03] (3.8e+03,3.87e+03] (3.87e+03,3.93e+03] (3.93e+03,4e+03]
3767.0 3833.5 3900.0 3967.0
In the past, i've used this function
evenbins <- function(x, bin.count=10, order=T) {
bin.size <- rep(length(x) %/% bin.count, bin.count)
bin.size <- bin.size + ifelse(1:bin.count <= length(x) %% bin.count, 1, 0)
bin <- rep(1:bin.count, bin.size)
if(order) {
bin <- bin[rank(x,ties.method="random")]
}
return(factor(bin, levels=1:bin.count, ordered=order))
}
and then i can run it with
v.bin <- evenbins(v, 60)
and check the sizes with
table(v.bin)
and see they all contain 66 or 67 elements. By default this will order the values just like cut will so each of the factor levels will have increasing values. If you want to bin them based on their original order,
v.bin <- evenbins(v, 60, order=F)
instead. This just split the data up in the order it appears
This result shows the 59 median values of the break-points. The 60 bin values are probably as close to equal as possible (but probably not exactly equal).
> sq <- seq(1, 4000, length = 60)
> sapply(2:length(sq), function(i) median(c(sq[i-1], sq[i])))
# [1] 34.88983 102.66949 170.44915 238.22881 306.00847 373.78814
# [7] 441.56780 509.34746 577.12712 644.90678 712.68644 780.46610
# ......
Actually, after checking, the bins are pretty darn close to being equal.
> unique(diff(sq))
# [1] 67.77966 67.77966 67.77966
Related
I essentially have two columns (vectors) with speed and accel in a data.frame as such:
speed acceleration
1 3.2694444 2.6539535522
2 3.3388889 2.5096979141
3 3.3888889 2.2722134590
4 3.4388889 1.9815256596
5 3.5000000 1.6777544022
6 3.5555556 1.3933215141
7 3.6055556 1.1439051628
8 3.6527778 0.9334115982
9 3.6722222 0.7561602592
I need to find for each value speed on the x axis (speed), what is the top 10% max values from the y axis (acceleration). This also needs to be in a specific interval. For example speed 3.2-3.4, 3.4-3.6, and so on. Can you please show me how a for loop would look like in this situation?
As #alistaire already pointed out, you have provided a very limited amount of data. So we first have to simulate I a bit more data based on which we can test our code.
set.seed(1)
# your data
speed <- c(3.2694444, 3.3388889, 3.3388889, 3.4388889, 3.5,
3.5555556, 3.6055556, 3.6527778, 3.6722222)
acceleration <- c(2.6539535522, 2.5096979141, 2.2722134590,
1.9815256596, 1.6777544022, 1.3933215141,
1.1439051628, 0.9334115982, 0.7561602592)
df <- data.frame(speed, acceleration)
# expand data.frame and add a little bit of noise to all values
# to make them 'unique'
df <- as.data.frame(do.call(
rbind,
replicate(15L, apply(df, 2, \(x) (x + runif(length(x), -1e-1, 1e-1) )),
simplify = FALSE)
))
The function create_intervals, as the name suggests, creates user-defined intervals. The rest of the code does the 'heavy lifting' and stores the desired result in out.
If you would like to have intervals of speed with equal widths, simply specify the number of groups (n_groups) you would like to have and leave the rest of the arguments (i.e. lwr, upr, and interval_span) unspecified.
# Cut speed into user-defined intervals
create_intervals <- \(n_groups = NULL, lwr = NULL, upr = NULL, interval_span = NULL) {
if (!is.null(lwr) & !is.null(upr) & !is.null(interval_span) & is.null(n_groups)) {
speed_low <- subset(df, speed < lwr, select = speed)
first_interval <- with(speed_low, c(min(speed), lwr))
middle_intervals <- seq(lwr + interval_span, upr - interval_span, interval_span)
speed_upp <- subset(df, speed > upr, select = speed)
last_interval <- with(speed_upp, c(upr, max(speed)))
intervals <- c(first_interval, middle_intervals, last_interval)
} else {
step <- with(df, c(max(speed) - min(speed))/n_groups)
intervals <- array(0L, dim = n_groups)
for(i in seq_len(n_groups)) {
intervals[i] <- min(df$speed) + i * step
}
}
return(intervals)
}
# three intervals with equal width
my_intervals <- create_intervals(n_groups = 3L)
# Compute values of speed when acceleration is greater then
# or equal to the 90th percentile
out <- lapply(1:(length(my_intervals)-1L), \(i) {
x <- subset(df, speed >= my_intervals[i] & speed <= my_intervals[i+1L])
x[x$acceleration >= quantile(x$acceleration, 0.9), ]
})
# function to round values to two decimal places
r <- \(x) format(round(x, 2), nsmall = 2L)
# assign names to each element of out
for(i in seq_along(out)) {
names(out)[i] <- paste0(r(my_intervals[i]), '-', r(my_intervals[i+1L]))
}
Output 1
> out
$`3.38-3.57`
speed acceleration
11 3.394378 2.583636
21 3.383631 2.267659
57 3.434123 2.300234
83 3.394886 2.580924
101 3.395459 2.460971
$`3.57-3.76`
speed acceleration
6 3.635234 1.447290
41 3.572868 1.618293
51 3.615017 1.420020
95 3.575412 1.763215
We could also compute the desired values of speed based on intervals that make more 'sense' than just equally spaced speed intervals, e.g. [min(speed), 3.3), [3.3, 3.45), [3.45, 3.6), and [3.6, max(speed)).
This can be accomplished by leaving n_groups unspecified and instead specify lwr, upr, and an interval_span that makes sense. For instance, it makes sense to have a interval span of 0.15 when the lower limit is 3.3 and the upper limit is 3.6.
# custom boundaries based on a lower limit and upper limit
my_intervals <- create_intervals(lwr = 3.3, upr = 3.6, interval_span = 0.15)
Output 2
> out
$`3.18-3.30`
speed acceleration
37 3.238781 2.696456
82 3.258691 2.722076
$`3.30-3.45`
speed acceleration
11 3.394378 2.583636
19 3.328292 2.711825
73 3.315306 2.644580
83 3.394886 2.580924
$`3.45-3.60`
speed acceleration
4 3.520530 2.018930
40 3.517329 2.032943
58 3.485247 2.079893
67 3.458031 2.078545
$`3.60-3.76`
speed acceleration
6 3.635234 1.447290
34 3.688131 1.218969
51 3.615017 1.420020
78 3.628465 1.348873
Note: use function(x) instead of \(x) if you use a version of R <4.1.0
I'm trying to implement a check for decreasing values of avg temperatures to see when the temperature starts falling. See the chart of temperatures here:
Here is the formula I'm trying to implement:
Here is my code to implement that formula:
temps <- read.delim("temps.txt")
date_avgs <- rowMeans(temps[2:length(temps)], dims=1, na.rm=T)
mu <- 87
threshold <- 86
constant <- 3
date_avgs
S <- 0 * date_avgs
for (i in 2:length(date_avgs)) {
value <- S[i-1] + (mu - date_avgs[i] - constant)
cat("\nvalue", value, "si", date_avgs[i], i)
S[i] <- max(0, value)
if(S[i] >= threshold){
#Once I hit this for the first time, that indicates at this index the temp is decreasing
cat("\nDecreased past my threshold!!!", S[i] ,i)
}
}
But I'm not able to detect the change as I expect. My formula doesn't get over the threshold until index 108, when it should get there around index 60.
Here is the plot of my S (or CUSUM) values:
Any ideas what I'm doing wrong in my formula?
I think the problem is mu <- mean(date_avgs) basically means of all the observations. But mu should be "mean of X if no change". Thus mu should be about 87 but according your code and plotted data seems to be 80 or less.
# simulated data
set.seed(4422)
date_avgs <- c(runif(60, 84, 92), 88-(1:50)-rnorm(50,0,4))
plot(date_avgs)
# setting constants
mu <- 87
threshold <- 86
constant <- 3
# after running for cycle
Index <- match(S[S >= threshold][1], S)
Index
[1] 75
# for data
> date_avgs[74]
[1] 73.41981
# Considering a lower threshold
# (as maximum allowable difference to detect trend 2 * C)
mu <- 87
threshold <- 6 # arbitrary
constant <- 3
# after running for cycle
Index <- match(S[S >= threshold][1], S)
Index
[1] 66
So I think code is fine, maybe the interpretation is not
I asked this question a year ago and got code for this "probability heatmap":
numbet <- 32
numtri <- 1e5
prob=5/6
#Fill a matrix
xcum <- matrix(NA, nrow=numtri, ncol=numbet+1)
for (i in 1:numtri) {
x <- sample(c(0,1), numbet, prob=c(prob, 1-prob), replace = TRUE)
xcum[i, ] <- c(i, cumsum(x)/cumsum(1:numbet))
}
colnames(xcum) <- c("trial", paste("bet", 1:numbet, sep=""))
mxcum <- reshape(data.frame(xcum), varying=1+1:numbet,
idvar="trial", v.names="outcome", direction="long", timevar="bet")
library(plyr)
mxcum2 <- ddply(mxcum, .(bet, outcome), nrow)
mxcum3 <- ddply(mxcum2, .(bet), summarize,
ymin=c(0, head(seq_along(V1)/length(V1), -1)),
ymax=seq_along(V1)/length(V1),
fill=(V1/sum(V1)))
head(mxcum3)
library(ggplot2)
p <- ggplot(mxcum3, aes(xmin=bet-0.5, xmax=bet+0.5, ymin=ymin, ymax=ymax)) +
geom_rect(aes(fill=fill), colour="grey80") +
scale_fill_gradient("Outcome", formatter="percent", low="red", high="blue") +
scale_y_continuous(formatter="percent") +
xlab("Bet")
print(p)
(May need to change this code slightly because of this)
This is almost exactly what I want. Except each vertical shaft should have different numbers of bins, ie the first should have 2, second 3, third 4 (N+1). In the graph shaft 6 +7 have the same number of bins (7), where 7 should have 8 (N+1).
If I'm right, the reason the code does this is because it is the observed data and if I ran more trials we would get more bins. I don't want to rely on the number of trials to get the correct number of bins.
How can I adapt this code to give the correct number of bins?
I have used R's dbinom to generate the frequency of heads for n=1:32 trials and plotted the graph now. It will be what you expect. I have read some of your earlier posts here on SO and on math.stackexchange. Still I don't understand why you'd want to simulate the experiment rather than generating from a binomial R.V. If you could explain it, it would be great! I'll try to work on the simulated solution from #Andrie to check out if I can match the output shown below. For now, here's something you might be interested in.
set.seed(42)
numbet <- 32
numtri <- 1e5
prob=5/6
require(plyr)
out <- ldply(1:numbet, function(idx) {
outcome <- dbinom(idx:0, size=idx, prob=prob)
bet <- rep(idx, length(outcome))
N <- round(outcome * numtri)
ymin <- c(0, head(seq_along(N)/length(N), -1))
ymax <- seq_along(N)/length(N)
data.frame(bet, fill=outcome, ymin, ymax)
})
require(ggplot2)
p <- ggplot(out, aes(xmin=bet-0.5, xmax=bet+0.5, ymin=ymin, ymax=ymax)) +
geom_rect(aes(fill=fill), colour="grey80") +
scale_fill_gradient("Outcome", low="red", high="blue") +
xlab("Bet")
The plot:
Edit: Explanation of how your old code from Andrie works and why it doesn't give what you intend.
Basically, what Andrie did (or rather one way to look at it) is to use the idea that if you have two binomial distributions, X ~ B(n, p) and Y ~ B(m, p), where n, m = size and p = probability of success, then, their sum, X + Y = B(n + m, p) (1). So, the purpose of xcum is to obtain the outcome for all n = 1:32 tosses, but to explain it better, let me construct the code step by step. Along with the explanation, the code for xcum will also be very obvious and it can be constructed in no time (without any necessity for for-loop and constructing a cumsum everytime.
If you have followed me so far, then, our idea is first to create a numtri * numbet matrix, with each column (length = numtri) having 0's and 1's with probability = 5/6 and 1/6 respectively. That is, if you have numtri = 1000, then, you'll have ~ 834 0's and 166 1's *for each of the numbet columns (=32 here). Let's construct this and test this first.
numtri <- 1e3
numbet <- 32
set.seed(45)
xcum <- t(replicate(numtri, sample(0:1, numbet, prob=c(5/6,1/6), replace = TRUE)))
# check for count of 1's
> apply(xcum, 2, sum)
[1] 169 158 166 166 160 182 164 181 168 140 154 142 169 168 159 187 176 155 151 151 166
163 164 176 162 160 177 157 163 166 146 170
# So, the count of 1's are "approximately" what we expect (around 166).
Now, each of these columns are samples of binomial distribution with n = 1 and size = numtri. If we were to add the first two columns and replace the second column with this sum, then, from (1), since the probabilities are equal, we'll end up with a binomial distribution with n = 2. Similarly, instead, if you had added the first three columns and replaced th 3rd column by this sum, you would have obtained a binomial distribution with n = 3 and so on...
The concept is that if you cumulatively add each column, then you end up with numbet number of binomial distributions (1 to 32 here). So, let's do that.
xcum <- t(apply(xcum, 1, cumsum))
# you can verify that the second column has similar probabilities by this:
# calculate the frequency of all values in 2nd column.
> table(xcum[,2])
0 1 2
694 285 21
> round(numtri * dbinom(2:0, 2, prob=5/6))
[1] 694 278 28
# more or less identical, good!
If you divide the xcum, we have generated thus far by cumsum(1:numbet) over each row in this manner:
xcum <- xcum/matrix(rep(cumsum(1:numbet), each=numtri), ncol = numbet)
this will be identical to the xcum matrix that comes out of the for-loop (if you generate it with the same seed). However I don't quite understand the reason for this division by Andrie as this is not necessary to generate the graph you require. However, I suppose it has something to do with the frequency values you talked about in an earlier post on math.stackexchange
Now on to why you have difficulties obtaining the graph I had attached (with n+1 bins):
For a binomial distribution with n=1:32 trials, 5/6 as probability of tails (failures) and 1/6 as the probability of heads (successes), the probability of k heads is given by:
nCk * (5/6)^(k-1) * (1/6)^k # where nCk is n choose k
For the test data we've generated, for n=7 and n=8 (trials), the probability of k=0:7 and k=0:8 heads are given by:
# n=7
0 1 2 3 4 5
.278 .394 .233 .077 .016 .002
# n=8
0 1 2 3 4 5
.229 .375 .254 .111 .025 .006
Why are they both having 6 bins and not 8 and 9 bins? Of course this has to do with the value of numtri=1000. Let's see what's the probabilities of each of these 8 and 9 bins by generating probabilities directly from the binomial distribution using dbinom to understand why this happens.
# n = 7
dbinom(7:0, 7, prob=5/6)
# output rounded to 3 decimal places
[1] 0.279 0.391 0.234 0.078 0.016 0.002 0.000 0.000
# n = 8
dbinom(8:0, 8, prob=5/6)
# output rounded to 3 decimal places
[1] 0.233 0.372 0.260 0.104 0.026 0.004 0.000 0.000 0.000
You see that the probabilities corresponding to k=6,7 and k=6,7,8 corresponding to n=7 and n=8 are ~ 0. They are very low in values. The minimum value here is 5.8 * 1e-7 actually (n=8, k=8). This means that you have a chance of getting 1 value if you simulated for 1/5.8 * 1e7 times. If you check the same for n=32 and k=32, the value is 1.256493 * 1e-25. So, you'll have to simulate that many values to get at least 1 result where all 32 outcomes are head for n=32.
This is why your results were not having values for certain bins because the probability of having it is very low for the given numtri. And for the same reason, generating the probabilities directly from the binomial distribution overcomes this problem/limitation.
I hope I've managed to write with enough clarity for you to follow. Let me know if you've trouble going through.
Edit 2:
When I simulated the code I've just edited above with numtri=1e6, I get this for n=7 and n=8 and count the number of heads for k=0:7 and k=0:8:
# n = 7
0 1 2 3 4 5 6 7
279347 391386 233771 77698 15763 1915 117 3
# n = 8
0 1 2 3 4 5 6 7 8
232835 372466 259856 104116 26041 4271 392 22 1
Note that, there are k=6 and k=7 now for n=7 and n=8. Also, for n=8, you have a value of 1 for k=8. With increasing numtri you'll obtain more of the other missing bins. But it'll require a huge amount of time/memory (if at all).
I want to perform winsorization in a dataframe like this:
event_date beta_before beta_after
2000-05-05 1.2911707054 1.3215648954
1999-03-30 0.5089734305 0.4269575657
2000-05-05 0.5414700258 0.5326762272
2000-02-09 1.5491034852 1.2839988507
1999-03-30 1.9380674599 1.6169735009
1999-03-30 1.3109909155 1.4468207148
2000-05-05 1.2576420753 1.3659492507
1999-03-30 1.4393018341 0.7417777965
2000-05-05 0.2624037804 0.3860641307
2000-05-05 0.5532216441 0.2618245169
2000-02-08 2.6642931822 2.3815576738
2000-02-09 2.3007578964 2.2626960407
2001-08-14 3.2681270302 2.1611010935
2000-02-08 2.2509121123 2.9481325199
2000-09-20 0.6624503316 0.947935581
2006-09-26 0.6431111805 0.8745333151
By winsorization I mean to find the max and min for beta_before for example. That value should be replaced by the second highest or second lowest value in the same column, without loosing the rest of the details in the observation. For example. In this case, in beta_before the max value is 3.2681270302 and should be replaced by 3.2681270302. The same process will be followed for the min and then for the beta_after variable. Therefore, only 2 values per column will be changes, the highest and the minimum, the rest will remain the same.
Any advice? I tried different approaches in plyr, but I ended up replacing the whole observation, which I don’t want to do. I would like to create 2 new variables, for example beta_before_winsorized and beta _after_winsorized
I thought winsorizing usually finds the value x% (typically 10%, 15%, or 20%) from the bottom of the ordered list, and replaces all the values below it with that value. Same with the top. Here you're just choosing the top and bottom value, but winsorizing usually involves specifying a percentage of values at the top and bottom to replace.
Here is a function that does the winsorzation you describe:
winsorize <- function(x) {
Min <- which.min(x)
Max <- which.max(x)
ord <- order(x)
x[Min] <- x[ord][2]
x[Max] <- x[ord][length(x)-1]
x
}
If you data are in a data frame dat, then we can windsoroize the data using your procedure via:
dat2 <- dat
dat2[, -1] <- sapply(dat[,-1], winsorize)
which results in:
R> dat2
event_date beta_before beta_after
1 2000-05-05 1.2911707 1.3215649
2 1999-03-30 0.5089734 0.4269576
3 2000-05-05 0.5414700 0.5326762
4 2000-02-09 1.5491035 1.2839989
5 1999-03-30 1.9380675 1.6169735
6 1999-03-30 1.3109909 1.4468207
7 2000-05-05 1.2576421 1.3659493
8 1999-03-30 1.4393018 0.7417778
9 2000-05-05 0.5089734 0.3860641
10 2000-05-05 0.5532216 0.3860641
11 2000-02-08 2.6642932 2.3815577
12 2000-02-09 2.3007579 2.2626960
13 2001-08-14 2.6642932 2.1611011
14 2000-02-08 2.2509121 2.3815577
15 2000-09-20 0.6624503 0.9479356
16 2006-09-26 0.6431112 0.8745333
I'm not sure where you got the value you suggest should replace the max in beta_before as the second highest is 2.6642932 in the snippet of data provided and that is what my function has used to replace with the maximum value with.
Note the function will only work if there is one minimum and maximum values respectively in each column owing to the way which.min() and which.max() are documented to work. If you have multiple entries taking the same max or min value then we would need something different:
winsorize2 <- function(x) {
Min <- which(x == min(x))
Max <- which(x == max(x))
ord <- order(x)
x[Min] <- x[ord][length(Min)+1]
x[Max] <- x[ord][length(x)-length(Max)]
x
}
should do it (latter is not tested).
Strictly speaking, "winsorization" is the act of replacing the most extreme data points with an acceptable percentile (as mentioned in some of the other answers). One fairly standard R function to do this is winsor from the psych package. Try:
dat$beta_before = psych::winsor(dat$beta_before, trim = 0.0625)
dat$beta_after = psych::winsor(dat$beta_after , trim = 0.0625)
I chose trim = to be 0.0625 (the 6.25th percentile and 93.75th percentile) because you only have 16 data points and you want to "rein in" the top and bottom ones: 1/16 = 0.0625
Note that this might make the extreme data equal to a percentile number which may or may not exist in your data set: the theoretical n-th percentile of the data.
The statar package works very well for this. Copying the relevant snippet from the readme file:
# winsorize (default based on 5 x interquartile range)
v <- c(1:4, 99)
winsorize(v)
winsorize(v, replace = NA)
winsorize(v, probs = c(0.01, 0.99))
winsorize(v, cutpoints = c(1, 50))
https://github.com/matthieugomez/statar
follow up from my previous point about actually replacing the to-be-trimmed values with value at trim position:
winsorized.sample<-function (x, trim = 0, na.rm = FALSE, ...)
{
if (!is.numeric(x) && !is.complex(x) && !is.logical(x)) {
warning("argument is not numeric or logical: returning NA")
return(NA_real_)
}
if (na.rm)
x <- x[!is.na(x)]
if (!is.numeric(trim) || length(trim) != 1L)
stop("'trim' must be numeric of length one")
n <- length(x)
if (trim > 0 && n) {
if (is.complex(x))
stop("trimmed sample is not defined for complex data")
if (any(is.na(x)))
return(NA_real_)
if (trim >= 0.5) {
warning("trim >= 0.5 is odd...trying it anyway")
}
lo <- floor(n * trim) + 1
hi <- n + 1 - lo
#this line would work for just trimming
# x <- sort.int(x, partial = unique(c(lo, hi)))[lo:hi]
#instead, we're going to replace what would be trimmed
#with value at trim position using the next 7 lines
idx<-seq(1,n)
myframe<-data.frame(idx,x)
myframe<-myframe[ order(x,idx),]
myframe$x[1:lo]<-x[lo]
myframe$x[hi:n]<-x[hi]
myframe<-myframe[ order(idx,x),]
x<-myframe$x
}
x
}
#test it
mydist<-c(1,20,1,5,2,40,5,2,6,1,5)
mydist2<-winsorized.sample(mydist, trim=.2)
mydist
mydist2
descStat(mydist)
descStat(mydist2)
I'm using the cut function to split my data in equal bins, it does the job but I'm not happy with the way it returns the values. What I need is the center of the bin not the upper and lower ends.
I've also tried to use cut2{Hmisc}, this gives me the center of each bins, but it divides the range of data in bins that contains the same numbers of observations, rather than being of the same length.
Does anyone have a solution to this?
It's not too hard to make the breaks and labels yourself, with something like this. Here since the midpoint is a single number, I don't actually return a factor with labels but instead a numeric vector.
cut2 <- function(x, breaks) {
r <- range(x)
b <- seq(r[1], r[2], length=2*breaks+1)
brk <- b[0:breaks*2+1]
mid <- b[1:breaks*2]
brk[1] <- brk[1]-0.01
k <- cut(x, breaks=brk, labels=FALSE)
mid[k]
}
There's probably a better way to get the bin breaks and midpoints; I didn't think about it very hard.
Note that this answer is different than Joshua's; his gives the median of the data in each bins while this gives the center of each bin.
> head(cut2(x,3))
[1] 16.666667 3.333333 16.666667 3.333333 16.666667 16.666667
> head(ave(x, cut(x,3), FUN=median))
[1] 18 2 18 2 18 18
Use ave like so:
set.seed(21)
x <- sample(0:20, 100, replace=TRUE)
xCenter <- ave(x, cut(x,3), FUN=median)
We can use smart_cut from package cutr:
devtools::install_github("moodymudskipper/cutr")
library(cutr)
Using #Joshua's sample data:
median by interval (same output as #Joshua except it's an ordered factor) :
smart_cut(x,3, "n_intervals", labels= ~ median(.))
# [1] 18 2 18 2 18 18 ...
# Levels: 2 < 11 < 18
center of each interval (same output as #Aaron except it's an ordered factor) :
smart_cut(x,3, "n_intervals", labels= ~ mean(.y))
# [1] 16.67 3.333 16.67 3.333 16.67 16.67 ...
# Levels: 3.333 < 10 < 16.67
mean of values by interval :
smart_cut(x,3, "n_intervals", labels= ~ mean(.))
# [1] 17.48 2.571 17.48 2.571 17.48 17.48 ...
# Levels: 2.571 < 11.06 < 17.48
labels can be a character vector just like in base::cut.default, but it can also be, as it is here, a function of 2 parameters, the first being the values contained in the bin, and the second the cut points of the bin.
more on cutr and smart_cut