Create new column from two column with logic in R? [closed] - r

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Looking for other way than ifelse.
How to create NewColumn like this:


As displayed in your picture, you want to paste together two columns. Assuming your dataframe is called df, you can do:
df$NewColumn <- paste(df$Column2,"",df$Column1)
Which will get you the outcome in the picture.

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How is it possible to add 15 to every figure in a column, in a tibble? [duplicate]

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I’m new to R and I’m trying to add 15 to every figure in my dataset for a specific column and was wondering how it’s possible to this. Any help would be much appreciated, thanks.

Asssuming you have a data.frame df with a column col that you want to increase:
df$col <- df$col + 15
No loop required, the fundamental objects in R are vectors.

How to order a data.drame with the variables' order in codebook [closed]

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If I have a data.frame that contain the variables that listed in df$Var. Is it a way for me to reorder my data col in the order of df$Var?
The df is looks like this:
Is it a way I can sort dt so the col in dt will in the order of var in df?
Thanks.

We can use factor with levels specified as the values in 'df1$Var'
dt1[order(factor(names(dt1), levels = df1$Var))]
Or use match
dt1[order(match(names(dt1), df1$Var))]

I need help transforming one dataframe to another [closed]

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I am trying to understand how to go about transforming dataframe in pic 1 into 2. How can i go about doing the transformation?

We can use gather with extract
library(tidyverse)
gather(df1, year, MatriculationRates, -1) %>%
extract(year, into = 'year', '[^0-9]+([0-9]+)')

R: Vector Group by Defined group [closed]

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I have a vector c("A","B","C",......) and a list list(c("A"),c("B","C"))
I want to get a vector c(1,2,2....)
Is there any function in some basic packages?

we can use merge
merge(stack(setNames(lst, seq_along(lst))), data.frame(values=v1))$ind

data.table complex manipulation with rows elimination [closed]

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Data sample is below: I have 3million rows.
Date,id,type,qty
9/30/14,1,’A’,10
9/30/14,2,’Z’,12
9/30/14,3,’B’,15
9/30/14,1,’B’,20
9/30/14,1,’Z’,20
9/30/14,1,’A’,20
9/30/14,2,’B’,20
9/30/14,3,’B’,5
9/30/14,3,’A’,40
I want result as below:
Date,id,type,Qty
9/30/14,1,A,20
9/30/14,1,B,20
9/30/14,2,B,20
9/30/14,3,B,5
9/30/14,3,’A’,40
Logic is below: On the same date, pick the latest qty (from the later record) for each id and type.Ignore types y and Z.

DT[,.(Qty=last(qty)),by=.(Date,id,type)][type!='Z'][order(id)]

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