As.Numeric() Removes Decimal Places in R, How to Change

as.numeric() removes decimal places in R, how to change?

R is basically following some basic configuration settings for printing the number of required digits. You can change this with the digits option as follows:

> options(digits=9)
> y <- as.character("0.912345678")
> as.numeric(y)
[1] 0.912345678

Small EDIT for clarity:
digits corresponds to the number of digits to display in total, and not just the number of digits after the comma.

For example,

> options(digits=9)
> y <- as.character("10.123456789")
> as.numeric(y)
[1] 10.1234568

In your example above the leading zero before the comma is not counted, this is why 9 digits was enough to display the complete number.

Formatting Decimal places in R

Background: Some answers suggested on this page (e.g., signif, options(digits=...)) do not guarantee that a certain number of decimals are displayed for an arbitrary number. I presume this is a design feature in R whereby good scientific practice involves showing a certain number of digits based on principles of "significant figures". However, in many domains (e.g., APA style, business reports) formatting requirements dictate that a certain number of decimal places are displayed. This is often done for consistency and standardisation purposes rather than being concerned with significant figures.

Solution:

The following code shows exactly two decimal places for the number x.

format(round(x, 2), nsmall = 2)

For example:

format(round(1.20, 2), nsmall = 2)
# [1] "1.20"
format(round(1, 2), nsmall = 2)
# [1] "1.00"
format(round(1.1234, 2), nsmall = 2)
# [1] "1.12"

A more general function is as follows where x is the number and k is the number of decimals to show. trimws removes any leading white space which can be useful if you have a vector of numbers.

specify_decimal <- function(x, k) trimws(format(round(x, k), nsmall=k))

E.g.,

specify_decimal(1234, 5)
# [1] "1234.00000"
specify_decimal(0.1234, 5)
# [1] "0.12340"

Discussion of alternatives:

The formatC answers and sprintf answers work fairly well. But they will show negative zeros in some cases which may be unwanted. I.e.,

formatC(c(-0.001), digits = 2, format = "f")
# [1] "-0.00"
sprintf(-0.001, fmt = '%#.2f')
# [1] "-0.00"

One possible workaround to this is as follows:

formatC(as.numeric(as.character(round(-.001, 2))), digits = 2, format = "f")
# [1] "0.00" 

Convert string to numeric defining the number of decimal digits

You didn't actually lose the digits; that's just how it is being printed to the console:

options(digits = 4)
R> as.numeric(res[[1]][1])
#[1] 44.52
## 
options(digits = 12)
R> as.numeric(res[[1]][1])
#[1] 44.524768336

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As pointed out in the comments by David Arenburg you can also use print(..., digits = <n>).

Convert character to number without the loss of decimal in R

All of the digits are still there. That is just the default printing method.

new.vec <- as.numeric(f1)
print(new.vec, digits=20)
#[1] 402313.01399128098 402896.30908451998 403165.63827027398
#[4] 403169.06116369402 402891.96329268801 402239.74412469601
#[7] 402271.54950727499 402313.01399128098

You can also change the default with options(digits = n).

More information here.

as.numeric is rounding off values

I think this is a representation problem, not an actual rounding problem ...

options("digits") ## 7

From ?options:

‘digits’: controls the number of digits to print when printing numeric values. It is a suggestion only. Valid values are
1...22 with default 7. See the note in ‘print.default’ about
values greater than 15.

digits can be reset either on a one-off basis, i.e. print(object,digits=...), or globally, i.e. options(digits=20) (20 is probably overkill but helps you see what's happening: based on the results below, 10 might serve your needs well.)

as.numeric(data1$colC)
[1] 4023108 3180863 2558778 2393736 1333148 1275627
print(as.numeric(data1$colC),digits=10)
[1] 4023107.87 3180863.42 2558777.81 2393736.25 1333148.48 1275627.13
print(as.numeric(data1$colC),digits=20)
[1] 4023107.8700000001118 3180863.4199999999255 2558777.8100000000559
[4] 2393736.2500000000000 1333148.4799999999814 1275627.1299999998882

Formatting decimal places in a character column. as.numeric erase the values in the column

I assume you are somewhere which uses a comma for a decimal point, and perhaps a decimal point in place of a thousands separator.

As an example:

df <- c(',958229561278528615818098193915712388824', '2,05561009284393218251509777394193942492', '2,72096803821411321343605598060792704404', '2,00324997757400185789440370684992098409')

First, remove any decimal points, because they may be thousands separators. Then, replace the comma with a decimal point:

as.numeric(gsub(',', '.', gsub('\\.', '', df)))

Edit: however, if you intend to use more than the first few decimal places, you may run into problems with precision. Look into the package Rmpfr if you need arbitrary precision.

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