How to Convert Only Some Positive Numbers to Negative Numbers (Conditional Recoding)

How to convert only SOME positive numbers to negative numbers (conditional recoding)?

new.Freq <- with(mydata, ifelse(Var1 <= 1, -Freq, Freq))

How to recode negative values in a set of variables based on if conditional statement in R?

You can use

df[, 2:5] <- abs(df[, 2:5])

Converting negative numbers to positive numbers but keeping positive numbers unchanged

The last part

negated = (~x + 1) & sign;

is wrong, you are going to get either 1 or 0, you have to create a mask with all
first 31 bits to 0 and only the last one to either 0 or 1.

Assuming that for you target you are dealing with 32 bit integers with 2
complement, you can do this:

#include <stdio.h>

// assuming 32bit, 2 complement
int sign_inverse(int n)
{
    int mask = ~n & 0x80000000U;

    if(n == 0)
        mask = 0;

    return (~n + 1) | mask;
}

int main(void)
{
    int a = 5;
    int b = -4;
    int c = 54;
    int d = 0;

    printf("sign_inverse(%d) = %d\n", a, sign_inverse(a));
    printf("sign_inverse(%d) = %d\n", b, sign_inverse(b));
    printf("sign_inverse(%d) = %d\n", c, sign_inverse(c));
    printf("sign_inverse(%d) = %d\n", d, sign_inverse(d));

    return 0;
}

but you need at least 1 if for the case of 0, because the mask for 0 is 0x80000000.

The output of this is:

$ ./b 
sign_inverse(5) = -5
sign_inverse(-4) = 4
sign_inverse(54) = -54
sign_inverse(0) = 0

IF statement to turn positive values into negative values in Excel

If longitude data is in column C (from C2 onwards, say) - then you can deploy a couple of synonymous techniques - depending upon your preference:

1. =if(C2>0,-C2,C2) : perhaps most intuitive
2. =-abs(C2) : parsimonious, kudos to Jadefalke (26/01/22 - commentary)

Array functions exist for these too - i.e. for a column of data C2:C10, you can enter (once) in the corresponding leading (top) cell =-abs(C2:C10). see here for details RE: Office 365 compatible vs. prior versions of Excel.

How to convert positive numbers to negative in Python?

If you want to force a number to negative, regardless of whether it's initially positive or negative, you can use:

    -abs(n)

Note that integer 0 will remain 0.

Count number of negative values based on a condition of another variable in R

base R

Using by:

by(df$dummy, df$value > 0, FUN = sum)

# df$value > 0: FALSE
# [1] 3
# --------------------------------------------------------------------- 
# df$value > 0: TRUE
# [1] 2

Using aggregate:

aggregate(dummy ~ value > 0, data = df, sum)

#   value > 0 dummy
# 1     FALSE     3
# 2      TRUE     2

---

dplyr

library(dplyr)
df %>% 
  group_by(sign = value > 0) %>% 
  summarise(sum = sum(dummy))

# A tibble: 2 x 2
#   sign    sum
#   <lgl> <int>
# 1 FALSE     3
# 2 TRUE      2

Or, using sign:

df %>% 
  group_by(sign = sign(value)) %>% 
  summarise(sum = sum(dummy))

# A tibble: 3 x 2
   sign   sum
  <dbl> <int>
1    -1     3
2     0     0
3     1     2

---

df <- structure(list(dummy = c(TRUE, FALSE, FALSE, FALSE, TRUE, TRUE, 
TRUE, FALSE, TRUE), value = c(-2, 3, 4, 2, -4.5, 9, -1, 0, 3)), class = "data.frame", row.names = c(NA, 
-9L))

Convert a positive number to negative in C#

How about

myInt = myInt * -1

Excel custom formatting positive/negative numbers with Thousand/Million/Billion (K/M/B) suffixes

Since it appears to not be possible with a one-stop solution (which while I think doing this without a one-stop is a little messy, but I also understand why they can't just magically understand every conceivable custom format iteration), I am opting for a two-step approach:

I will have 3 custom formats. One for the positive numbers with suffixes, another for the negative numbers with suffixes, and a third that is just the "standard" positive/negative number format (displayed in the question). I will then use a series of two or three conditional formatting rules to determine which of these custom formats will be displayed.

Personally, I am going to use the +/- format as the cell's format, then apply two conditional rules that change it to the two suffix variations, but I could see the argument for using conditional formats for all three.

Thanks for the feedback and the reminder that conditional formatting exists to aid with this very kind of issue.

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