CODEWITHSUNDEEP
rshinydata.table
IVIM
IVIM

Reputation: 2367

How to take R filter condition from user in Shiny

Please see Reprodex below. How to make it run? Is that possible with data.table or any other way?

---
title: "Interactive Filtering of 'mtcars'"
output: html_document
runtime: shiny
---


```{r}
library(shiny)
library(data.table)
dt <- data.table(mtcars)

textInput("filter", "Enter filter using R syntax:", "",
          placeholder="(cyl==6) & (hp>100)")


h5("Works:")

renderTable({ 
  dt[(cyl==6) & (hp>100)]
})

h5("Does not Work:")

renderTable({
  q = quote("(cyl==6) & (hp>100)")
  dt[eval(q)]
})

renderTable({
  dt[eval(quote(input$filter))]
})

Upvotes: 1

Views: 27

Answers (1)

bdbmax
bdbmax

Reputation: 341

Maybe this can help resolve your problem:

dt <- mtcars
f <- "(dt$cyl==6) & (dt$hp>100)"

dt[(dt$cyl==6) & (dt$hp>100), ]
                mpg cyl  disp  hp drat    wt  qsec vs am gear carb
Mazda RX4      21.0   6 160.0 110 3.90 2.620 16.46  0  1    4    4
Mazda RX4 Wag  21.0   6 160.0 110 3.90 2.875 17.02  0  1    4    4
Hornet 4 Drive 21.4   6 258.0 110 3.08 3.215 19.44  1  0    3    1
Valiant        18.1   6 225.0 105 2.76 3.460 20.22  1  0    3    1
Merc 280       19.2   6 167.6 123 3.92 3.440 18.30  1  0    4    4
Merc 280C      17.8   6 167.6 123 3.92 3.440 18.90  1  0    4    4
Ferrari Dino   19.7   6 145.0 175 3.62 2.770 15.50  0  1    5    6
# OR
dt[eval(parse(text = f)), ]
                mpg cyl  disp  hp drat    wt  qsec vs am gear carb
Mazda RX4      21.0   6 160.0 110 3.90 2.620 16.46  0  1    4    4
Mazda RX4 Wag  21.0   6 160.0 110 3.90 2.875 17.02  0  1    4    4
Hornet 4 Drive 21.4   6 258.0 110 3.08 3.215 19.44  1  0    3    1
Valiant        18.1   6 225.0 105 2.76 3.460 20.22  1  0    3    1
Merc 280       19.2   6 167.6 123 3.92 3.440 18.30  1  0    4    4
Merc 280C      17.8   6 167.6 123 3.92 3.440 18.90  1  0    4    4
Ferrari Dino   19.7   6 145.0 175 3.62 2.770 15.50  0  1    5    6

You should be able to use eval(parse(text = ...)) to wrap over your input$filter !

Also, right now in your textInput you only put a placeholder. I suggest you switch it to a default value using the value = argument.

And so, this would work:

---
title: "Interactive Filtering of 'mtcars'"
output: html_document
runtime: shiny
---


```{r}
library(shiny)
library(data.table)
dt <- data.table(mtcars)

textInput("filter", "Enter filter using R syntax:", value="(cyl==6) & (hp>100)",
          placeholder="(cyl==6) & (hp>100)", )

renderTable({
  dt[eval(parse(text = input$filter))]
})

Upvotes: 2

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