Conditional Number Formatting in R-CodePudding

Can anyone tell me how I can conditionally format my data.table so that numbers >= 1000 do not have decimal places and those below 1000 only have one decimal place?

Here's an image of my data.table

CodePudding user response：

You could use tibbles which allows to print vectors as you like, see vignette("pillar", package = "vctrs").

As shown in this answer on a similar need :

You can get basic control over how a vector is printed in a tibble by providing a format() method

To answer your question, you could create a custom_numeric class extending numeric, see vignette("s3-vector", package = "vctrs"):

library(vctrs)
library(data.table)
library(tibble)

data <- data.table(a=1.11,b=100.11,c=1000.11)

custom_numeric<- function(x = numeric()) {
  vec_assert(x, numeric())
  new_vctr(x, class = "vctrs_custom_numeric")
}

# Create custom format
format.vctrs_custom_numeric<- function(x,...) {
  sapply(vec_data(x),function(x) {if (x>1000) round(x) else x})
}

# Rename custom type name in column header
vec_ptype_abbr.vctrs_custom_numeric <- function(x) {
  "numeric"
}

# Apply custom type to all numeric columns
data[,(names(data)):= lapply(.SD,function(col) if (is.numeric(col)) custom_numeric(col) else col )]

# Convert to tibble
tibble::tibble(data)

#> # A tibble: 1 × 3
#>           a         b         c
#>   <numeric> <numeric> <numeric>
#> 1      1.11    100.11      1000

CodePudding user response：

Using the dev version of data.table (1.14.3), you could implement a numeric method for format_col generic. More information about customized printing of data.table is available at HERE

Here is an example:

library(data.table)
update.dev.pkg()          # to use the dev version

# sample data
set.seed(123)
dt = data.table(a=rnorm(10, 1000, 100), b=rnorm(10, 1000, 100))

# run dt before creating a numeric method for format_col generic
dt
#             a         b
#         <num>     <num>
#  1:  943.9524 1122.4082
#  2:  976.9823 1035.9814
#  3: 1155.8708 1040.0771
#  4: 1007.0508 1011.0683
#  5: 1012.9288  944.4159
#  6: 1171.5065 1178.6913
#  7: 1046.0916 1049.7850
#  8:  873.4939  803.3383
#  9:  931.3147 1070.1356
# 10:  955.4338  952.7209

# create a numeric method for format_col
format_col.numeric = function(x, ...) {
  ifelse(abs(x)<=1000, round(x), round(x, 1))
}

# printing after
dt
#          a      b
#      <num>  <num>
#  1:    944 1122.4
#  2:    977   1036
#  3: 1155.9 1040.1
#  4: 1007.1 1011.1
#  5: 1012.9    944
#  6: 1171.5 1178.7
#  7: 1046.1 1049.8
#  8:    873    803
#  9:    931 1070.1
# 10:    955    953