When averaging speeds, the harmonic mean is in need. The straight forward AVG() approach is wrong, the arithmetic mean yields the wrong result for average velocity. There is no predefined function for the harmonic mean, but it could be achieved with this query: SELECT segment, COUNT(*)/SUM(1e0/speed) AS avg_speed FROM T GROUP BY segment SQL Fiddle … Read more
float x,i=~(257<<23),a,s,t;main(int n,char**f){a=-i;f=fopen(f[1],”r” );for(n=0;fscanf(f,”%f”,&x)>0;n++,s+=x,x<i?i=x:0,x>a?a=x:0,t+=x*x); printf(“%d %f %f %f %f\n”,n,a,i,s/n,sqrtf(t/n));} Sorry for the long code. Didn’t have time to make it shorter. 1 solved Read file with floats, calculate size, max, min, mean, median and standard deviaton in C [closed]
I am not going to write the code for you, but this will probably help. If I am understanding the question correctly you are trying to take a big block of text (paragraph) split it into sentences then get the average len of characters in each sentence. So: 1) Break text block into sentences. Here … Read more
With a data.frame named dat that looked like: rank name country category sales profits assets marketvalue 21 21 DaimlerChrysler Germany Consumer_dur 157.13 5.12 195.58 47.43 Try (untested d/t the numerous spaces in the text preventing read.table from making sense of it): aggregate(dat[ , c(“sales”, “profits”, “assets”, “marketvalue”)], # cols to aggregate dat[“country”], # group column … Read more
The crucial point in OP’s approach is the staggered aggregation (see the related question row not consolidating duplicates in R when using multiple months in Date Filter). The OP wants to aggregate data across a number of files which apparently are too large to be loaded altogether and combined into a large data.table. Instead, each … Read more