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How to find the proportion of each value for a cross tab obtained from a data frame in R?
To find the proportion of each value for a cross tab obtained from a data frame, we can use prop.table function. Suppose we have a data frame called df that contains three columns, two categorical say C1 and C2 and one numerical say Y then the cross tab will be created by using the command xtabs(Y~.,df). Now the proportion of each value can be found by using prop.table(xtabs(Y~.,df),1).
Example1
Consider the below data frame −
f1<-sample(LETTERS[1:5],20,replace=TRUE) f2<-sample(letters[1:5],20,replace=TRUE) y1<-rpois(20,50) df1<-data.frame(f1,f2,y1) df1
Output
f1 f2 y1 1 D e 51 2 C c 59 3 B c 47 4 D a 45 5 E c 45 6 D e 49 7 E c 49 8 E d 63 9 E b 46 10 C c 49 11 A e 66 12 B c 60 13 E d 51 14 B e 49 15 C c 49 16 D a 64 17 A a 55 18 C a 44 19 E a 51 20 A d 56
Creating cross tab for data in df1 −
xtabs(y1~.,df1) f2
f1 a b c d e A 55 0 0 56 66 B 0 0 107 0 49 C 44 0 157 0 0 D 109 0 0 0 100 E 51 46 94 114 0
Creating proportion table for data in df1 −
prop.table(xtabs(y1~.,df1),1) f2
f1 a b c d e A 0.3107345 0.0000000 0.0000000 0.3163842 0.3728814 B 0.0000000 0.0000000 0.6858974 0.0000000 0.3141026 C 0.2189055 0.0000000 0.7810945 0.0000000 0.0000000 D 0.5215311 0.0000000 0.0000000 0.0000000 0.4784689 E 0.1672131 0.1508197 0.3081967 0.3737705 0.0000000
Example 2
v1<-sample(c("Asian","African","Europe","Oceania","Antarctica"),20,replace=TRUE)
v2<-sample(c("Male","Female"),20,replace=TRUE)
y2<-sample(2000:1000,20)
df2<-data.frame(v1,v2,y2)
df2Output
v1 v2 y2 1 African Female 1904 2 Oceania Male 1097 3 Asian Male 1883 4 African Male 1384 5 Europe Female 1208 6 Oceania Male 1494 7 Oceania Female 1436 8 Antarctica Male 1858 9 Asian Female 1396 10 Antarctica Female 1905 11 Europe Female 1995 12 Oceania Female 1045 13 Oceania Female 1810 14 Europe Female 1471 15 African Female 1543 16 Oceania Female 1519 17 African Female 1912 18 Asian Female 1520 19 Oceania Male 1604 20 African Male 1096
Creating cross tab for data in df2 −
xtabs(y2~.,df2) v2
v1 Female Male African 5359 2480 Antarctica 1905 1858 Asian 2916 1883 Europe 4674 0 Oceania 5810 4195
Creating proportion table for data in df2 −
prop.table(xtabs(y2~.,df2),1) v2
v1 Female Male African 0.6836331 0.3163669 Antarctica 0.5062450 0.4937550 Asian 0.6076266 0.3923734 Europe 1.0000000 0.0000000 Oceania 0.5807096 0.4192904
Updated on: 06-Mar-2021
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