Problems picking out minimum values of a column of a matrix

[drshinez]

I am a beginer and i have problems picking out minimum values ​​of a column of a matrix..
Sad attempts :

a<-c(1,4,6,4,1)
b<-c(4,16,24,16,4)
c<-c(6,24,36,24,6)
d<-c(4,16,24,16,4)
e<-c(1,4,6,4,1)
cbind(a,b,c,d,e)
gauss.filter<-cbind(a,b,c,d,e)
gauss_std<-gauss.filter/sum(gauss.filter)
min(gauss.filter)
min(gauss.filter[1,2,3,4])
min(gauss.filter(c(1,2,3,4)))
dplyr::filter(min(gauss.filter))
dplyr::filter(gauss.filter,min(iris))
dplyr::filter(gauss.filter,min(c(1,2,3,4,5))
dplyr::filter(gauss.filter,min(1-5))
dplyr::filter(row(gauss.filter)
min(row(gauss.filter))
min(row.names(gauss.filter))
min(row(1-5))
dplyr::filter(gauss.filter(min(row())))
gauss.filter(min(iris))

[ttrodrigz]

Hi there, if I understand you correctly, you want to return the minimum value for each column of your gauss.filter matrix?

If so, I would suggest using the apply() function. As the name suggests, this function applies a function over a margin of a matrix like object. It would look something like this:

a <- c(1, 4, 6, 4, 1)
b <- c(4, 16, 24, 16, 4)
c <- c(6, 24, 36, 24, 6)
d <- c(4, 16, 24, 16, 4)
e <- c(1, 4, 6, 4, 1)

gauss.filter <- cbind(a, b, c, d, e)

apply(
    X = gauss.filter,
    MARGIN = 2, 
    FUN = min
)
#> a b c d e 
#> 1 4 6 4 1

The apply function above can be read as, "return the minimum value of each column of the gauss.filter matrix." (If MARGIN had been set to 1, it would have returned the minum value for each row instead of each column.

As an aside, I would strongly suggest taking a look at this post which has a few solid resources for learning R. Good luck!

[joels]

To do this with tidyverse functions, you could do the following:

library(tidyverse)

gauss.filter <- cbind(a, b, c, d, e)

gauss.filter %>% 
  as.data.frame() %>% 
  summarise_all(min)

  a b c d e
1 1 4 6 4 1

gauss.filter is a matrix, but dplyr functions expect a data frame, so we first convert it to a data frame. Then summarise_all runs the min function on every column of gauss.filter.