change value to percentage of row in R [duplicate]

Answer 1

Seems a fair case for

df/rowSums(df)
#           A         B         C
# A 0.9000000 0.1000000 0.0000000
# B 0.3333333 0.3333333 0.3333333
# C 0.3333333 0.3333333 0.3333333

If you don't want so many digits after the dot set options(digits = 2) or use print(df/rowSums(df), digits = 2) or use round

round(df/rowSums(df), 2)
#      A    B    C
# A 0.90 0.10 0.00
# B 0.33 0.33 0.33
# C 0.33 0.33 0.33

Or as suggested by @akrun

round(prop.table(as.matrix(df1),1),2)