library(magrittr) # %>% pipe
txt = 
  c("20220404,板橋,38,40,0.1,4288,120,20220404,三重,25,60,0.2,4286,125",
    "20220404,板橋,38,40,0.1,4288,120,20220404,三重,25,60,0.2,4286,125",
    "20220404,板橋,38,40,0.1,4288,120,20220404,三重,25,60,0.2,4286,125",
    "20220404,板橋,38,40,0.1,4288,120,20220404,三重,25,60,0.2,4286,125")
strsplit(txt, ",") %>%
  do.call("c", .) %>%
  matrix(byrow = T, ncol = 7)
#      [,1]       [,2]   [,3] [,4] [,5]  [,6]   [,7] 
# [1,] "20220404" "板橋" "38" "40" "0.1" "4288" "120"
# [2,] "20220404" "三重" "25" "60" "0.2" "4286" "125"
# [3,] "20220404" "板橋" "38" "40" "0.1" "4288" "120"
# [4,] "20220404" "三重" "25" "60" "0.2" "4286" "125"
# [5,] "20220404" "板橋" "38" "40" "0.1" "4288" "120"
# [6,] "20220404" "三重" "25" "60" "0.2" "4286" "125"
# [7,] "20220404" "板橋" "38" "40" "0.1" "4288" "120"
# [8,] "20220404" "三重" "25" "60" "0.2" "4286" "125"