How to simply multiply two columns of a dataframe?

Question

My input is

a<-c(1,2,3,4)
b<-c(1,2,4,8)
df<-data.frame(cbind(a,b))

My output should be

a<-c(1,2,3,4)
b<-c(1,2,4,8)
d<-c(1,4,12,32)
df<-data.frame(cbind(a,b,c))

can i simply say df$a * df$b please help. I am getting an issue with duplication. they are getting multiplied in matrix form and there is also issue with different length columns.

You don't need the `cbind()` calls when building data.frames; the `data.frame()` constructor function automatically takes each argument as a separate column. — bgoldst, Aug 05 '15 at 06:31

score 16 · Accepted Answer · answered Aug 05 '15 at 06:55

16

In Base R:

df$c <- df$a * df$b

or df$c <- with(df, a * b)

In Dplyr:

df <- df %>% mutate(c = a * b)

answered Aug 05 '15 at 06:55

phiver

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score 2 · Answer 2 · edited Aug 06 '18 at 11:21

2

You must assign df$a * df$b to a new column in the dataframe.

df$c<-df$a*df$b

This adds a new column (df$c) which contains column a multiplied by column b.

edited Aug 06 '18 at 11:21

dpel

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answered Aug 05 '15 at 06:38

rosswalter

21
2

How to simply multiply two columns of a dataframe?

2 Answers2

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