R , Looping through a dataframe , creating a new one with additional content - r

Question

Caution, quite new to R - but I really would like to do this in R instead of java.
My csv-file (Swedish redlist for species 2020 ) looks like this:
id,svenskt,latin,Organismgrupp,Kategori,Observationer,Landskapstyp,status_abbrev,Rodlistekriterium
249012,,Abia candens,stekel,Art,3,"Jordbrukslandskap (J) - Stor betydelse, Skog (S) - Har betydelse",DD,
249014,,Abia lonicerae,stekel,Art,2,Skog (S) - Stor betydelse,DD,
261452,,Abia nitens,stekel,Art,0,Jordbrukslandskap (J) - Stor betydelse,DD,
The whole csv-file can be download from SLU by pressing the button 'skapa csv-fil'.
The interesting columns for me is only the 'id' and the 'status_abbrev' columns.
I would like to use those columns to update my db-table, doing something like this:
sql<- paste("update redlist SET status_abbrev='",abbrev,"' ","where id=",id,sep="")
reading the csv-file with this command:
library(dplyr)
redlist <- read.csv("rodlistade_arter_tampered_2.csv",header=TRUE);
dat <- select(redlist,'id', 'status_abbrev')
the output from the 3 first lines would be:
redlist is a dataframe, contains the csv with header.
datis a dataframe , contains a subset of redlist (id and status_abbrev).
But which library would be best to iterate through the 'dat' data-frame to be able to create something like this ?
iterating and picking out abbrev and id and creating the below string for each row - (in the end I would like to write these strings to an sql-batch file and update the roughy 5660-records)
sql<- paste("update redlist SET status_abbrev='",abbrev,"' ","where id=",id,sep="")
so that my resulting string would be like this (then iterating through the whole file) :
update redlist SET status_abbrev=DD where id=249012
screenshot of redlist and dat -
best,i

Answer 1

Using dplyr::mutate() and glue::glue() you can create the strings like this
library(tidyverse)
library(glue)
#>
#> Attaching package: 'glue'
#> The following object is masked from 'package:dplyr':
#>
#> collapse
str <- 'id,svenskt,latin,Organismgrupp,Kategori,Observationer,Landskapstyp,status_abbrev,Rodlistekriterium
249012,,Abia candens,stekel,Art,3,"Jordbrukslandskap (J) - Stor betydelse, Skog (S) - Har betydelse",DD,
249014,,Abia lonicerae,stekel,Art,2,Skog (S) - Stor betydelse,DD,
261452,,Abia nitens,stekel,Art,0,Jordbrukslandskap (J) - Stor betydelse,DD,'
df <- read_csv(str)
df2 <- df %>%
mutate(sql_string = glue("update redlist SET status_abbrev='{status_abbrev}' where id={id}"))
df2
#> # A tibble: 3 x 10
#> id svenskt latin Organismgrupp Kategori Observationer Landskapstyp
#> <dbl> <lgl> <chr> <chr> <chr> <dbl> <chr>
#> 1 249012 NA Abia… stekel Art 3 Jordbruksla…
#> 2 249014 NA Abia… stekel Art 2 Skog (S) - …
#> 3 261452 NA Abia… stekel Art 0 Jordbruksla…
#> # … with 3 more variables: status_abbrev <chr>, Rodlistekriterium <lgl>,
#> # sql_string <glue>
df2 %>% pull(sql_string)
#> update redlist SET status_abbrev='DD' where id=249012
#> update redlist SET status_abbrev='DD' where id=249014
#> update redlist SET status_abbrev='DD' where id=261452
Created on 2020-07-27 by the reprex package (v0.3.0)
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For database integration, have a look at DBI.