CODEWITHSUNDEEP
r
dondapati
dondapati

Reputation: 849

Build the dataframe with conditional vector in R

I have two vectors 

a <- c(18,19,19,19,21,21,22,23,24,25,26,27,28,30,31,35,36,37)
b <- c(19,25,31,37)

I need the data frame following format:

a      b
18     19
19     19
19     19
19     19
21     25
21     25
22     25
23     25
24     25
25     25
26     31
27     31
28     31 
30     31
31     31
35     37
36     37
37     37

Here value 19 in vector b repeat up to the value 19 in vector a. After that 21(in a) is the greater than 19 ,so the next value of 25(in b) is be repeat until the 25(in a ) in similar way construct the dataframe.

Thank you.

Upvotes: 2

Views: 220

Answers (2)

Julius Vainora
Julius Vainora

Reputation: 48191

Alternatively,

data.frame(a, b = sapply(a, function(x) b[x <= b][1]))
#     a  b
# 1  18 19
# 2  19 19
# 3  19 19
# 4  19 19
# 5  21 25
# 6  21 25
# 7  22 25
# 8  23 25
# 9  24 25
# 10 25 25
# 11 26 31
# 12 27 31
# 13 28 31
# 14 30 31
# 15 31 31
# 16 35 37
# 17 36 37
# 18 37 37

Upvotes: 2

akrun
akrun

Reputation: 886948

We can get the position index from findInterval, use that to create the times for the rep

i1 <- findInterval(b, a)
data.frame(a, b = rep(b, c(i1[1], diff(i1))))
#    a  b
#1  18 19
#2  19 19
#3  19 19
#4  19 19
#5  21 25
#6  21 25
#7  22 25
#8  23 25
#9  24 25
#10 25 25
#11 26 31
#12 27 31
#13 28 31
#14 30 31
#15 31 31
#16 35 37
#17 36 37
#18 37 37

Upvotes: 4

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