On 06/13/2012 11:41 PM, Nympha Nymphaea wrote:
Dear R-helpers,
I'm stuck with a little problem that surely has an easy solution but I
can't think of a way to solve it. I'd really appreciate any help you can
offer me!
I'll provide a small example. Given a dataframe data.txt that looks like
this:
ID freq Var Var_mean Ratio_mean Var_median
Ratio_median Var_sum Ratio_min Var_max Ratio_max Var_min
Ratio_sum
134 5 2.140 0.447 4.784 0.272 7.881 2.237 0.957
0.833 2.568 0.187 11.437
30 4 1.743 0.450 3.873 0.358 4.869 1.799 0.968
0.915 1.904 0.169 10.329
137 4 1.401 0.304 4.614 0.310 4.514 1.215 1.153
0.480 2.921 0.114 12.268
9 3 0.065 0.023 2.849 0.021 3.108 0.069 0.950
0.030 2.137 0.017 3.799
35 3 0.192 0.067 2.849 0.025 7.756 0.202 0.950
0.153 1.258 0.025 7.756
95 3 1.365 0.360 3.792 0.335 4.073 1.080 1.264
0.484 2.820 0.261 5.237
120 3 5.171 1.891 2.735 0.542 9.532 5.672 0.912
4.970 1.040 0.160 32.408
123 3 0.721 0.226 3.182 0.155 4.661 0.679 1.061
0.372 1.939 0.153 4.704
133 3 3.242 0.918 3.531 0.921 3.519 2.754 1.177
1.551 2.090 0.282 11.512
136 3 1.058 0.371 2.850 0.337 3.141 1.113 0.950
0.449 2.358 0.328 3.225
140 3 5.935 1.877 3.162 0.327 18.167 5.630 1.054
5.114 1.160 0.189 31.332
141 3 0.974 0.325 2.997 0.160 6.092 0.975 0.999
0.661 1.473 0.154 6.330
147 3 3.207 0.798 4.018 0.951 3.373 2.394 1.339
1.148 2.793 0.296 10.840
2 2 3.859 2.020 1.911 2.020 1.911 4.039 0.955
3.714 1.039 0.326 11.851
8 2 0.017 0.009 1.900 0.009 1.900 0.018 0.950
0.014 1.266 0.005 3.799
10 2 0.096 0.060 1.603 0.060 1.603 0.120 0.802
0.060 1.599 0.060 1.607
26 2 7.308 0.504 14.500 0.504 14.500 1.008 7.250
0.813 8.990 0.195 37.459
46 2 9.070 7.542 1.203 7.542 1.203 15.085 0.601
7.576 1.197 7.509 1.208
49 2 9.485 5.035 1.884 5.035 1.884 10.070 0.942
9.406 1.008 0.664 14.289
63 2 21.308 13.956 1.527 13.956 1.527 27.912
0.763 14.148 1.506 13.764 1.548
And I need to calculate the mean of every column whose name starts with
Ratio_.
That is, I need to calculate the mean of the columns Ratio_mean (3.4882),
Ratio_median (5.2607), Ratio_sum (1.29985), Ratio_min (2.1533), Ratio_max
(11.1469).
But I would like to have the results just at once, in one column or one
after the other (and not to run the code for every single result).
I do have almost 200 columns that start with Ratio_, so doing it by hand
it's really burdensome...
I tried with a "for" loop:
for (x in 1:5) {
x<- with(data, c(Ratio_mean, Ratio_median, Ratio_sum, Ratio_max,
Ratio_min))
Mean<- with(data mean(x))
print(Mean)
}
But the result is:
[1] 4.66979
[1] 4.66979
[1] 4.66979
[1] 4.66979
[1] 4.66979
which is the mean of all the columns together. I would like to obtain the
mean of every column in each line:
[1] 3.4882
[1] 5.2607
[1] 1.29985
[1] 2.1533
[1] 11.1469
I think my problem is that I don't know how to assign correctly the
variable x. Does anyone know if that is possible or an alternative way to
get that result?
Hi Nympha,
Try this:
nn<-read.table("nn.dat",header=TRUE)
for(variable in grep("Ratio_",names(nn),fixed=TRUE))
print(mean(nn[,variable]))
Jim
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