How to separate variable "race" to make histograms for another variable

Question

I have the following DataFrame:

head(SB_xlsx)

##   patnum hospstay    lowph pltct  race  bwt gest        inout twn lol magsulf
## 1      1       34       NA   100 white 1250   35 born at duke   0  NA      NA
## 2      2        9 7.250000   244 white 1370   32 born at duke   0  NA      NA
## 3      3       -2 7.059998   114 black  620   23 born at duke   0  NA      NA
## 4      4       40 7.250000   182 black 1480   32 born at duke   0  NA      NA
## 5      5        2 6.969997    54 black  925   28 born at duke   0  NA      NA
## 6      6       62 7.189999    NA white  940   28 born at duke   0  NA      NA
##   meth toc  delivery apg1 vent pneumo pda cld    sex dead
## 1    0   0 abdominal    8    0      0   0   0 female    0
## 2    1   0 abdominal    7    0      0   0   0 female    0
## 3    0   1   vaginal    1    1      0   0  NA female    1
## 4    1   0   vaginal    8    0      0   0   0   male    0
## 5    0   0 abdominal    5    1      1   0   0 female    1
## 6    1   0 abdominal    8    1      0   0   0 female    0

I need to create 4 histograms comparing birth weight (bwt) to each of the 4 races ("white", "black", "native american", and "oriental") under the "race" variable. How would I need to go about separating out the races so I could make the histograms for bwt?

I had to make a histogram for all of the bwts regardless of race, which the code is shown below. I know how to formulate histograms, but I'm not sure how to separate out races so I can make the 4 race specific ones.

hist(SB_xlsx$bwt, ylab="frequency", xlab="Birth Weight", main="Histogram of Birth Weight")