Antwort: RE: Interdependencies of variable types, logical expressions and NA

2 messages · PIKAL Petr

Thu, Apr 28, 2016 5:31 AM #

Hi

your initial ds

'data.frame':   2 obs. of  3 variables:
 $ var1: num  1 1
 $ var2: logi  TRUE FALSE
 $ var3: logi  NA NA

first result

'data.frame':   2 obs. of  6 variables:
 $ var1             : num  1 1
 $ var2             : logi  TRUE FALSE
 $ var3             : logi  NA NA
 $ value_and_logical: logi  TRUE TRUE
 $ logical_and_na   : logi  TRUE NA
 $ value_and_na     : logi  TRUE TRUE

1 is considered as TRUE therefore OR gives TRUE TRUE in first case, TRUE NA in second and TRUE TRUE in third

Changing to factor changes var 2 to NA (I am not sure why)

'data.frame':   2 obs. of  3 variables:
 $ var1: Factor w/ 2 levels "NOT ok","OK": 2 2
 $ var2: Factor w/ 2 levels "NOT ok","OK": NA NA
 $ var3: Factor w/ 2 levels "NOT ok","OK": NA NA

And this results to warning

Warning message:
In Ops.factor(ds$var1, ds$var2) : '|' not meaningful for factors

Warning message:
In Ops.factor(ds$var2, ds$var3) : '|' not meaningful for factors

Warning message:
In Ops.factor(ds$var1, ds$var3) : '|' not meaningful for factors

'data.frame':   2 obs. of  6 variables:
 $ var1             : Factor w/ 2 levels "NOT ok","OK": 2 2
 $ var2             : Factor w/ 2 levels "NOT ok","OK": NA NA
 $ var3             : Factor w/ 2 levels "NOT ok","OK": NA NA
 $ value_and_logical: logi  NA NA
 $ logical_and_na   : logi  NA NA
 $ value_and_na     : logi  NA NA

so | operation is not valid for factor variables and results to NA values.

Cheers
Petr

-----Original Message-----
From: G.Maubach at weinwolf.de [mailto:G.Maubach at weinwolf.de]
Sent: Thursday, April 28, 2016 12:00 PM
To: PIKAL Petr <petr.pikal at precheza.cz>
Subject: Antwort: RE: [R] Interdependencies of variable types, logical
expressions and NA

Hi Petr,

many thanks for your reply.

Yes it's interesting. I did not understand what the truth table wanted to
say due to 4 columns instead of 3. But know I got it.

The other thing is that logical expessions with NA work differently on
different types of variables as my example code shows:

-- cut --
# Truth table for logicals and NA

var2 <- c(TRUE, FALSE)
var3 <- c(NA, NA)
var1 <- c(1, 1)
ds <- data.frame(var1, var2, var3)
ds

ds$value_and_logical <- ifelse(ds$var1 | ds$var2, TRUE, FALSE)
ds$logical_and_na <- ifelse(ds$var2 | ds$var3, TRUE, FALSE)
ds$value_and_na <- ifelse(ds$var1 | ds$var3, TRUE, FALSE)

print(ds)

ds$var1 <- factor(ds$var1, levels = c(0, 1), labels = c("NOT ok", "OK"))
ds$var2 <- factor(ds$var2, levels = c(0, 1), labels = c("NOT ok", "OK"))
ds$var3 <- factor(ds$var3, levels = c(0, 1), labels = c("NOT ok", "OK"))

ds$value_and_logical <- ifelse(ds$var1 | ds$var2, TRUE, FALSE)
ds$logical_and_na <- ifelse(ds$var2 | ds$var3, TRUE, FALSE)
ds$value_and_na <- ifelse(ds$var1 | ds$var3, TRUE, FALSE)

print(ds)
-- cut --

Additionally the warning message that this script issues was not displayed
in my production code, but only in this test code.

Also: Is "<NA>" the same as "NA"?

Kind regards

Georg




Von:    PIKAL Petr <petr.pikal at precheza.cz>
An:     "G.Maubach at weinwolf.de" <G.Maubach at weinwolf.de>,
"r-help at r-project.org" <r-help at r-project.org>,
Datum:  28.04.2016 10:02
Betreff:        RE: [R] Interdependencies of variable types, logical
expressions and NA



Sorry
these

T&NA = T (you can decide that regardless value in NA the result must be T)
F&NA = NA (you cannot decide hence NA)

should be

T | NA = T (you can decide that regardless value in NA the result must be
T)
F | NA = NA (you cannot decide hence NA)

Cheers
Petr

-----Original Message-----
From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of PIKAL

Petr

Sent: Thursday, April 28, 2016 9:42 AM
To: G.Maubach at weinwolf.de; r-help at r-project.org
Subject: Re: [R] Interdependencies of variable types, logical

expressions and

NA

Hi

Your script is not reproducible.

Creating Check_U_0__Kd_1_2011 from Umsatz_2011 and Kunde01_2011
Error in ifelse(Kunden01[[Umsatz]] == 0 & Kunden01[[Kunde]] == 1, 1, 0)

  object 'Kunden01' not found

This is interesting
x <- c(NA, FALSE, TRUE)
names(x) <- as.character(x)
outer(x, x, "&") ## AND table
       <NA> FALSE  TRUE
<NA>     NA FALSE    NA
FALSE FALSE FALSE FALSE
TRUE     NA FALSE  TRUE

I am not sure, but the logic for AND is to return TRUE only when both
expressions are TRUE.

so
T&T = T
F&F = F
T&NA = NA (you cannot decide hence NA)
F&NA = F (you can decide that regardless of NA the result must be F)

outer(x, x, "|") ## OR  table
      <NA> FALSE TRUE
<NA>    NA    NA TRUE
FALSE   NA FALSE TRUE
TRUE  TRUE  TRUE TRUE

OTOH the logic for OR table is that if one of the expressions is TRUE

the result

must be TRUE
T | T = T
F | F = F
T&NA = T (you can decide that regardless value in NA the result must be

T)

F&NA = NA (you cannot decide hence NA)

And I believe that all your results can be explained by this logic.

Cheers
Petr

-----Original Message-----
From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of
G.Maubach at weinwolf.de
Sent: Thursday, April 28, 2016 9:08 AM
To: r-help at r-project.org
Subject: [R] Interdependencies of variable types, logical expressions

and

NA

Hi All,

my script tries to do the following on factors:

## Check for case 3: Umsatz = 0 & Kunde = 1
for (year in 2011:2015) {

+   Umsatz <- paste0("Umsatz_", year)
+   Kunde <- paste0("Kunde01_", year)
+   Check <- paste0("Check_U_0__Kd_1_", year)
+
+   cat('Creating', Check, 'from', Umsatz, "and", Kunde, '\n')
+
+   Kunden01[[ Check ]] <- ifelse(Kunden01[[ Umsatz ]] == 0 &
+                                 Kunden01[[ Kunde ]] == 1,
+                                 1, 0
+                                 )
+   Kunden01[[ Check ]] <- factor(Kunden01[[ Check ]],
+                                 levels=c(1, 0),
+                                 labels= c("Check 0", "OK")
+                                 )
+
+ }
Creating Check_U_0__Kd_1_2011 from Umsatz_2011 and Kunde01_2011
Creating Check_U_0__Kd_1_2012 from Umsatz_2012 and Kunde01_2012
Creating Check_U_0__Kd_1_2013 from Umsatz_2013 and Kunde01_2013
Creating Check_U_0__Kd_1_2014 from Umsatz_2014 and Kunde01_2014
Creating Check_U_0__Kd_1_2015 from Umsatz_2015 and Kunde01_2015

table(Kunden01$Check_U_0__Kd_1_2011, useNA = "ifany")

Check 0      OK    <NA>
      1      16      13

table(Kunden01$Check_U_0__Kd_1_2012, useNA = "ifany")

Check 0      OK    <NA>
      1      17      12

table(Kunden01$Check_U_0__Kd_1_2013, useNA = "ifany")

Check 0      OK    <NA>
      2      17      13

table(Kunden01$Check_U_0__Kd_1_2014, useNA = "ifany")

Check 0      OK    <NA>
      1      15      14

table(Kunden01$Check_U_0__Kd_1_2015, useNA = "ifany")

Check 0      OK    <NA>
      2      15      13

Kunden01$Check_U_0__Kd_1_all <-

ifelse(Kunden01$Check_U_0__Kd_1_2011 ==
1 |
+                                        Kunden01$Check_U_0__Kd_1_2012

==

1 |
+                                        Kunden01$Check_U_0__Kd_1_2013

==

1 |
+                                        Kunden01$Check_U_0__Kd_1_2014

==

1 |
+                                        Kunden01$Check_U_0__Kd_1_2015

==

1,
+                                        1, 0)

table(Kunden01$Check_U_0__Kd_1_all, useNA = "ifany")

    0  <NA>
    7    23

(Ann.: I made the values up. But the relations equal real world data.)

I had expected to get back a factor or at least a numeric variable
containing 0, 1 and NA, instead 1 is not included.

I searched the web for information on the treatment of logical

expressions

when the data contains NA. I found:

1.
https://stat.ethz.ch/R-manual/R-devel/library/base/html/NA.html
Examples
# Some logical operations do not return NA
c(TRUE, FALSE) & NA
c(TRUE, FALSE) | NA

2.
https://stat.ethz.ch/R-manual/R-devel/library/base/html/Logic.html
NA is a valid logical object. Where a component of x or y is NA, the
result will be NA if the outcome is ambiguous. In other words NA &

TRUE

evaluates to NA, but NA & FALSE evaluates to FALSE. See the examples
below.

## construct truth tables :
x <- c(NA, FALSE, TRUE)
names(x) <- as.character(x)
outer(x, x, "&") ## AND table
outer(x, x, "|") ## OR  table
Ann. Not very useful. How should it be read?

3.
http://www.ats.ucla.edu/stat/r/faq/missing.htm
Good explanation for NA in general and in analysis, but no information
about NA in logical expressions.

Then I made some tests with different data types and variables with

NA:

-- cut --

# 2016-04-27-001_truth_table_for_logicals_and_NA.R

# Test 1
var2 <- c(TRUE, FALSE)
var3 <- c(NA, NA)
var1 <- c(1, 1)
ds <- data.frame(var1, var2, var3)
ds

ds$value_and_logical <- ifelse(ds$var1 | ds$var2, TRUE, FALSE)
ds$logical_and_na <- ifelse(ds$var2 | ds$var3, TRUE, FALSE)
ds$value_and_na <- ifelse(ds$var1 | ds$var3, TRUE, FALSE)

print(ds)
# Output
# var1  var2 var3 value_and_logical logical_and_na value_and_na
# 1    1  TRUE   NA              TRUE           TRUE         TRUE
# 2    1 FALSE   NA              TRUE             NA         TRUE

# Test 2
ds$var1 <- factor(ds$var1, levels = c(0, 1), labels = c("NOT ok",

"OK"))

ds$var2 <- factor(ds$var2, levels = c(0, 1), labels = c("NOT ok",

"OK"))

ds$var3 <- factor(ds$var3, levels = c(0, 1), labels = c("NOT ok",

"OK"))

ds$value_and_logical <- ifelse(ds$var1 | ds$var2, TRUE, FALSE)
ds$logical_and_na <- ifelse(ds$var2 | ds$var3, TRUE, FALSE)
ds$value_and_na <- ifelse(ds$var1 | ds$var3, TRUE, FALSE)

# Output (abbrev.)
# Warning message:
#  In Ops.factor(ds$var1, ds$var3) : ?|? ist nicht sinnvoll f?r

Faktoren

print(ds)
# Output
# var1 var2 var3 value_and_logical logical_and_na value_and_na
# 1   OK <NA> <NA>                NA             NA           NA
# 2   OK <NA> <NA>                NA             NA           NA

-- cut --

I had expected to get the same result in Test 2 as in Test 1.

Where can I find information and documentation about NA handling in
logical expressions on different variable types?

Kind regards

Georg

______________________________________________

________________________________
Tento e-mail a jak?koliv k n?mu p?ipojen? dokumenty jsou d?v?rn? a jsou
ur?eny pouze jeho adres?t?m.
Jestli?e jste obdr?el(a) tento e-mail omylem, informujte laskav?
neprodlen? jeho odes?latele. Obsah tohoto emailu i s p??lohami a jeho
kopie vyma?te ze sv?ho syst?mu.
Nejste-li zam??len?m adres?tem tohoto emailu, nejste opr?vn?ni tento
email
jakkoliv u??vat, roz?i?ovat, kop?rovat ?i zve?ej?ovat.
Odes?latel e-mailu neodpov?d? za eventu?ln? ?kodu zp?sobenou
modifikacemi
?i zpo?d?n?m p?enosu e-mailu.

V p??pad?, ?e je tento e-mail sou??st? obchodn?ho jedn?n?:
- vyhrazuje si odes?latel pr?vo ukon?it kdykoliv jedn?n? o uzav?en?
smlouvy, a to z jak?hokoliv d?vodu i bez uveden? d?vodu.
- a obsahuje-li nab?dku, je adres?t opr?vn?n nab?dku bezodkladn? p?ijmout;
Odes?latel tohoto e-mailu (nab?dky) vylu?uje p?ijet? nab?dky ze strany
p??jemce s dodatkem ?i odchylkou.
- trv? odes?latel na tom, ?e p??slu?n? smlouva je uzav?ena teprve
v?slovn?m dosa?en?m shody na v?ech jej?ch n?le?itostech.
- odes?latel tohoto emailu informuje, ?e nen? opr?vn?n uzav?rat za
spole?nost ??dn? smlouvy s v?jimkou p??pad?, kdy k tomu byl p?semn?
zmocn?n nebo p?semn? pov??en a takov? pov??en? nebo pln? moc byly
adres?tovi tohoto emailu p??padn? osob?, kterou adres?t zastupuje,
p?edlo?eny nebo jejich existence je adres?tovi ?i osob? j?m zastoupen?
zn?m?.

This e-mail and any documents attached to it may be confidential and are
intended only for its intended recipients.
If you received this e-mail by mistake, please immediately inform its
sender. Delete the contents of this e-mail with all attachments and its
copies from your system.
If you are not the intended recipient of this e-mail, you are not
authorized to use, disseminate, copy or disclose this e-mail in any
manner.
The sender of this e-mail shall not be liable for any possible damage
caused by modifications of the e-mail or by delay with transfer of the
email.

In case that this e-mail forms part of business dealings:
- the sender reserves the right to end negotiations about entering into a
contract in any time, for any reason, and without stating any reasoning.
- if the e-mail contains an offer, the recipient is entitled to
immediately accept such offer; The sender of this e-mail (offer) excludes
any acceptance of the offer on the part of the recipient containing any
amendment or variation.
- the sender insists on that the respective contract is concluded only
upon an express mutual agreement on all its aspects.
- the sender of this e-mail informs that he/she is not authorized to enter
into any contracts on behalf of the company except for cases in which
he/she is expressly authorized to do so in writing, and such authorization
or power of attorney is submitted to the recipient or the person
represented by the recipient, or the existence of such authorization is
known to the recipient of the person represented by the recipient.

________________________________
Tento e-mail a jak?koliv k n?mu p?ipojen? dokumenty jsou d?v?rn? a jsou ur?eny pouze jeho adres?t?m.
Jestli?e jste obdr?el(a) tento e-mail omylem, informujte laskav? neprodlen? jeho odes?latele. Obsah tohoto emailu i s p??lohami a jeho kopie vyma?te ze sv?ho syst?mu.
Nejste-li zam??len?m adres?tem tohoto emailu, nejste opr?vn?ni tento email jakkoliv u??vat, roz?i?ovat, kop?rovat ?i zve?ej?ovat.
Odes?latel e-mailu neodpov?d? za eventu?ln? ?kodu zp?sobenou modifikacemi ?i zpo?d?n?m p?enosu e-mailu.

V p??pad?, ?e je tento e-mail sou??st? obchodn?ho jedn?n?:
- vyhrazuje si odes?latel pr?vo ukon?it kdykoliv jedn?n? o uzav?en? smlouvy, a to z jak?hokoliv d?vodu i bez uveden? d?vodu.
- a obsahuje-li nab?dku, je adres?t opr?vn?n nab?dku bezodkladn? p?ijmout; Odes?latel tohoto e-mailu (nab?dky) vylu?uje p?ijet? nab?dky ze strany p??jemce s dodatkem ?i odchylkou.
- trv? odes?latel na tom, ?e p??slu?n? smlouva je uzav?ena teprve v?slovn?m dosa?en?m shody na v?ech jej?ch n?le?itostech.
- odes?latel tohoto emailu informuje, ?e nen? opr?vn?n uzav?rat za spole?nost ??dn? smlouvy s v?jimkou p??pad?, kdy k tomu byl p?semn? zmocn?n nebo p?semn? pov??en a takov? pov??en? nebo pln? moc byly adres?tovi tohoto emailu p??padn? osob?, kterou adres?t zastupuje, p?edlo?eny nebo jejich existence je adres?tovi ?i osob? j?m zastoupen? zn?m?.

This e-mail and any documents attached to it may be confidential and are intended only for its intended recipients.
If you received this e-mail by mistake, please immediately inform its sender. Delete the contents of this e-mail with all attachments and its copies from your system.
If you are not the intended recipient of this e-mail, you are not authorized to use, disseminate, copy or disclose this e-mail in any manner.
The sender of this e-mail shall not be liable for any possible damage caused by modifications of the e-mail or by delay with transfer of the email.

In case that this e-mail forms part of business dealings:
- the sender reserves the right to end negotiations about entering into a contract in any time, for any reason, and without stating any reasoning.
- if the e-mail contains an offer, the recipient is entitled to immediately accept such offer; The sender of this e-mail (offer) excludes any acceptance of the offer on the part of the recipient containing any amendment or variation.
- the sender insists on that the respective contract is concluded only upon an express mutual agreement on all its aspects.
- the sender of this e-mail informs that he/she is not authorized to enter into any contracts on behalf of the company except for cases in which he/she is expressly authorized to do so in writing, and such authorization or power of attorney is submitted to the recipient or the person represented by the recipient, or the existence of such authorization is known to the recipient of the person represented by the recipient.

PIKAL Petr

Thu, Apr 28, 2016 6:29 AM #

Hi

?factor
help page says rather cryptically

The encoding of the vector happens as follows. First all the values in exclude are removed from levels. If x[i] equals levels[j], then the i-th element of the result is j. If no match is found for x[i] in levels (which will happen for excluded values) then the i-th element of the result is set to NA.

So if you specify levels when calling factor, each value not mentioned in levels is changed to NA

Factors are useful but sometimes their behaviour is rather tricky.

[1] 2 2 2

[1] 1 1
Levels: 0 1

[1] 2 2

[1] 0    1    <NA>
Levels: 0 1

[1]  1  2 NA  2

Cheers
Petr

-----Original Message-----
From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of PIKAL Petr
Sent: Thursday, April 28, 2016 2:32 PM
To: G.Maubach at weinwolf.de
Cc: r-help at r-project.org
Subject: Re: [R] Antwort: RE: Interdependencies of variable types, logical
expressions and NA

Hi

your initial ds

str(ds)

'data.frame':   2 obs. of  3 variables:
 $ var1: num  1 1
 $ var2: logi  TRUE FALSE
 $ var3: logi  NA NA

first result

str(ds)

'data.frame':   2 obs. of  6 variables:
 $ var1             : num  1 1
 $ var2             : logi  TRUE FALSE
 $ var3             : logi  NA NA
 $ value_and_logical: logi  TRUE TRUE
 $ logical_and_na   : logi  TRUE NA
 $ value_and_na     : logi  TRUE TRUE

1 is considered as TRUE therefore OR gives TRUE TRUE in first case, TRUE NA
in second and TRUE TRUE in third

Changing to factor changes var 2 to NA (I am not sure why)

str(ds)

'data.frame':   2 obs. of  3 variables:
 $ var1: Factor w/ 2 levels "NOT ok","OK": 2 2
 $ var2: Factor w/ 2 levels "NOT ok","OK": NA NA
 $ var3: Factor w/ 2 levels "NOT ok","OK": NA NA

And this results to warning

ds$value_and_logical <- ifelse(ds$var1 | ds$var2, TRUE, FALSE)

Warning message:
In Ops.factor(ds$var1, ds$var2) : '|' not meaningful for factors

ds$logical_and_na <- ifelse(ds$var2 | ds$var3, TRUE, FALSE)

Warning message:
In Ops.factor(ds$var2, ds$var3) : '|' not meaningful for factors

ds$value_and_na <- ifelse(ds$var1 | ds$var3, TRUE, FALSE)

Warning message:
In Ops.factor(ds$var1, ds$var3) : '|' not meaningful for factors

str(ds)

'data.frame':   2 obs. of  6 variables:
 $ var1             : Factor w/ 2 levels "NOT ok","OK": 2 2
 $ var2             : Factor w/ 2 levels "NOT ok","OK": NA NA
 $ var3             : Factor w/ 2 levels "NOT ok","OK": NA NA
 $ value_and_logical: logi  NA NA
 $ logical_and_na   : logi  NA NA
 $ value_and_na     : logi  NA NA

so | operation is not valid for factor variables and results to NA values.

Cheers
Petr

-----Original Message-----
From: G.Maubach at weinwolf.de [mailto:G.Maubach at weinwolf.de]
Sent: Thursday, April 28, 2016 12:00 PM
To: PIKAL Petr <petr.pikal at precheza.cz>
Subject: Antwort: RE: [R] Interdependencies of variable types, logical
expressions and NA

Hi Petr,

many thanks for your reply.

Yes it's interesting. I did not understand what the truth table wanted to
say due to 4 columns instead of 3. But know I got it.

The other thing is that logical expessions with NA work differently on
different types of variables as my example code shows:

-- cut --
# Truth table for logicals and NA

var2 <- c(TRUE, FALSE)
var3 <- c(NA, NA)
var1 <- c(1, 1)
ds <- data.frame(var1, var2, var3)
ds

ds$value_and_logical <- ifelse(ds$var1 | ds$var2, TRUE, FALSE)
ds$logical_and_na <- ifelse(ds$var2 | ds$var3, TRUE, FALSE)
ds$value_and_na <- ifelse(ds$var1 | ds$var3, TRUE, FALSE)

print(ds)

ds$var1 <- factor(ds$var1, levels = c(0, 1), labels = c("NOT ok", "OK"))
ds$var2 <- factor(ds$var2, levels = c(0, 1), labels = c("NOT ok", "OK"))
ds$var3 <- factor(ds$var3, levels = c(0, 1), labels = c("NOT ok", "OK"))

ds$value_and_logical <- ifelse(ds$var1 | ds$var2, TRUE, FALSE)
ds$logical_and_na <- ifelse(ds$var2 | ds$var3, TRUE, FALSE)
ds$value_and_na <- ifelse(ds$var1 | ds$var3, TRUE, FALSE)

print(ds)
-- cut --

Additionally the warning message that this script issues was not displayed
in my production code, but only in this test code.

Also: Is "<NA>" the same as "NA"?

Kind regards

Georg




Von:    PIKAL Petr <petr.pikal at precheza.cz>
An:     "G.Maubach at weinwolf.de" <G.Maubach at weinwolf.de>,
"r-help at r-project.org" <r-help at r-project.org>,
Datum:  28.04.2016 10:02
Betreff:        RE: [R] Interdependencies of variable types, logical
expressions and NA



Sorry
these

T&NA = T (you can decide that regardless value in NA the result must be T)
F&NA = NA (you cannot decide hence NA)

should be

T | NA = T (you can decide that regardless value in NA the result must be
T)
F | NA = NA (you cannot decide hence NA)

Cheers
Petr

-----Original Message-----
From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of PIKAL

Petr

Sent: Thursday, April 28, 2016 9:42 AM
To: G.Maubach at weinwolf.de; r-help at r-project.org
Subject: Re: [R] Interdependencies of variable types, logical

expressions and

NA

Hi

Your script is not reproducible.

Creating Check_U_0__Kd_1_2011 from Umsatz_2011 and Kunde01_2011
Error in ifelse(Kunden01[[Umsatz]] == 0 & Kunden01[[Kunde]] == 1, 1, 0)

  object 'Kunden01' not found

This is interesting
x <- c(NA, FALSE, TRUE)
names(x) <- as.character(x)
outer(x, x, "&") ## AND table
       <NA> FALSE  TRUE
<NA>     NA FALSE    NA
FALSE FALSE FALSE FALSE
TRUE     NA FALSE  TRUE

I am not sure, but the logic for AND is to return TRUE only when both
expressions are TRUE.

so
T&T = T
F&F = F
T&NA = NA (you cannot decide hence NA)
F&NA = F (you can decide that regardless of NA the result must be F)

outer(x, x, "|") ## OR  table
      <NA> FALSE TRUE
<NA>    NA    NA TRUE
FALSE   NA FALSE TRUE
TRUE  TRUE  TRUE TRUE

OTOH the logic for OR table is that if one of the expressions is TRUE

the result

must be TRUE
T | T = T
F | F = F
T&NA = T (you can decide that regardless value in NA the result must be

T)

F&NA = NA (you cannot decide hence NA)

And I believe that all your results can be explained by this logic.

Cheers
Petr

-----Original Message-----
From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of
G.Maubach at weinwolf.de
Sent: Thursday, April 28, 2016 9:08 AM
To: r-help at r-project.org
Subject: [R] Interdependencies of variable types, logical expressions

and

NA

Hi All,

my script tries to do the following on factors:

## Check for case 3: Umsatz = 0 & Kunde = 1
for (year in 2011:2015) {

+   Umsatz <- paste0("Umsatz_", year)
+   Kunde <- paste0("Kunde01_", year)
+   Check <- paste0("Check_U_0__Kd_1_", year)
+
+   cat('Creating', Check, 'from', Umsatz, "and", Kunde, '\n')
+
+   Kunden01[[ Check ]] <- ifelse(Kunden01[[ Umsatz ]] == 0 &
+                                 Kunden01[[ Kunde ]] == 1,
+                                 1, 0
+                                 )
+   Kunden01[[ Check ]] <- factor(Kunden01[[ Check ]],
+                                 levels=c(1, 0),
+                                 labels= c("Check 0", "OK")
+                                 )
+
+ }
Creating Check_U_0__Kd_1_2011 from Umsatz_2011 and

Kunde01_2011

Creating Check_U_0__Kd_1_2012 from Umsatz_2012 and

Kunde01_2012

Creating Check_U_0__Kd_1_2013 from Umsatz_2013 and

Kunde01_2013

Creating Check_U_0__Kd_1_2014 from Umsatz_2014 and

Kunde01_2014

Creating Check_U_0__Kd_1_2015 from Umsatz_2015 and

Kunde01_2015

table(Kunden01$Check_U_0__Kd_1_2011, useNA = "ifany")

Check 0      OK    <NA>
      1      16      13

table(Kunden01$Check_U_0__Kd_1_2012, useNA = "ifany")

Check 0      OK    <NA>
      1      17      12

table(Kunden01$Check_U_0__Kd_1_2013, useNA = "ifany")

Check 0      OK    <NA>
      2      17      13

table(Kunden01$Check_U_0__Kd_1_2014, useNA = "ifany")

Check 0      OK    <NA>
      1      15      14

table(Kunden01$Check_U_0__Kd_1_2015, useNA = "ifany")

Check 0      OK    <NA>
      2      15      13

Kunden01$Check_U_0__Kd_1_all <-

ifelse(Kunden01$Check_U_0__Kd_1_2011 ==
1 |
+                                        Kunden01$Check_U_0__Kd_1_2012

==

1 |
+                                        Kunden01$Check_U_0__Kd_1_2013

==

1 |
+                                        Kunden01$Check_U_0__Kd_1_2014

==

1 |
+                                        Kunden01$Check_U_0__Kd_1_2015

==

1,
+                                        1, 0)

table(Kunden01$Check_U_0__Kd_1_all, useNA = "ifany")

    0  <NA>
    7    23

(Ann.: I made the values up. But the relations equal real world data.)

I had expected to get back a factor or at least a numeric variable
containing 0, 1 and NA, instead 1 is not included.

I searched the web for information on the treatment of logical

expressions

when the data contains NA. I found:

1.
https://stat.ethz.ch/R-manual/R-devel/library/base/html/NA.html
Examples
# Some logical operations do not return NA
c(TRUE, FALSE) & NA
c(TRUE, FALSE) | NA

2.
https://stat.ethz.ch/R-manual/R-devel/library/base/html/Logic.html
NA is a valid logical object. Where a component of x or y is NA, the
result will be NA if the outcome is ambiguous. In other words NA &

TRUE

evaluates to NA, but NA & FALSE evaluates to FALSE. See the examples
below.

## construct truth tables :
x <- c(NA, FALSE, TRUE)
names(x) <- as.character(x)
outer(x, x, "&") ## AND table
outer(x, x, "|") ## OR  table
Ann. Not very useful. How should it be read?

3.
http://www.ats.ucla.edu/stat/r/faq/missing.htm
Good explanation for NA in general and in analysis, but no information
about NA in logical expressions.

Then I made some tests with different data types and variables with

NA:

-- cut --

# 2016-04-27-001_truth_table_for_logicals_and_NA.R

# Test 1
var2 <- c(TRUE, FALSE)
var3 <- c(NA, NA)
var1 <- c(1, 1)
ds <- data.frame(var1, var2, var3)
ds

ds$value_and_logical <- ifelse(ds$var1 | ds$var2, TRUE, FALSE)
ds$logical_and_na <- ifelse(ds$var2 | ds$var3, TRUE, FALSE)
ds$value_and_na <- ifelse(ds$var1 | ds$var3, TRUE, FALSE)

print(ds)
# Output
# var1  var2 var3 value_and_logical logical_and_na value_and_na
# 1    1  TRUE   NA              TRUE           TRUE         TRUE
# 2    1 FALSE   NA              TRUE             NA         TRUE

# Test 2
ds$var1 <- factor(ds$var1, levels = c(0, 1), labels = c("NOT ok",

"OK"))

ds$var2 <- factor(ds$var2, levels = c(0, 1), labels = c("NOT ok",

"OK"))

ds$var3 <- factor(ds$var3, levels = c(0, 1), labels = c("NOT ok",

"OK"))

ds$value_and_logical <- ifelse(ds$var1 | ds$var2, TRUE, FALSE)
ds$logical_and_na <- ifelse(ds$var2 | ds$var3, TRUE, FALSE)
ds$value_and_na <- ifelse(ds$var1 | ds$var3, TRUE, FALSE)

# Output (abbrev.)
# Warning message:
#  In Ops.factor(ds$var1, ds$var3) : ?|? ist nicht sinnvoll f?r

Faktoren

print(ds)
# Output
# var1 var2 var3 value_and_logical logical_and_na value_and_na
# 1   OK <NA> <NA>                NA             NA           NA
# 2   OK <NA> <NA>                NA             NA           NA

-- cut --

I had expected to get the same result in Test 2 as in Test 1.

Where can I find information and documentation about NA handling in
logical expressions on different variable types?

Kind regards

Georg

______________________________________________

________________________________
Tento e-mail a jak?koliv k n?mu p?ipojen? dokumenty jsou d?v?rn? a jsou ur?eny pouze jeho adres?t?m.
Jestli?e jste obdr?el(a) tento e-mail omylem, informujte laskav? neprodlen? jeho odes?latele. Obsah tohoto emailu i s p??lohami a jeho kopie vyma?te ze sv?ho syst?mu.
Nejste-li zam??len?m adres?tem tohoto emailu, nejste opr?vn?ni tento email jakkoliv u??vat, roz?i?ovat, kop?rovat ?i zve?ej?ovat.
Odes?latel e-mailu neodpov?d? za eventu?ln? ?kodu zp?sobenou modifikacemi ?i zpo?d?n?m p?enosu e-mailu.

V p??pad?, ?e je tento e-mail sou??st? obchodn?ho jedn?n?:
- vyhrazuje si odes?latel pr?vo ukon?it kdykoliv jedn?n? o uzav?en? smlouvy, a to z jak?hokoliv d?vodu i bez uveden? d?vodu.
- a obsahuje-li nab?dku, je adres?t opr?vn?n nab?dku bezodkladn? p?ijmout; Odes?latel tohoto e-mailu (nab?dky) vylu?uje p?ijet? nab?dky ze strany p??jemce s dodatkem ?i odchylkou.
- trv? odes?latel na tom, ?e p??slu?n? smlouva je uzav?ena teprve v?slovn?m dosa?en?m shody na v?ech jej?ch n?le?itostech.
- odes?latel tohoto emailu informuje, ?e nen? opr?vn?n uzav?rat za spole?nost ??dn? smlouvy s v?jimkou p??pad?, kdy k tomu byl p?semn? zmocn?n nebo p?semn? pov??en a takov? pov??en? nebo pln? moc byly adres?tovi tohoto emailu p??padn? osob?, kterou adres?t zastupuje, p?edlo?eny nebo jejich existence je adres?tovi ?i osob? j?m zastoupen? zn?m?.

This e-mail and any documents attached to it may be confidential and are intended only for its intended recipients.
If you received this e-mail by mistake, please immediately inform its sender. Delete the contents of this e-mail with all attachments and its copies from your system.
If you are not the intended recipient of this e-mail, you are not authorized to use, disseminate, copy or disclose this e-mail in any manner.
The sender of this e-mail shall not be liable for any possible damage caused by modifications of the e-mail or by delay with transfer of the email.

In case that this e-mail forms part of business dealings:
- the sender reserves the right to end negotiations about entering into a contract in any time, for any reason, and without stating any reasoning.
- if the e-mail contains an offer, the recipient is entitled to immediately accept such offer; The sender of this e-mail (offer) excludes any acceptance of the offer on the part of the recipient containing any amendment or variation.
- the sender insists on that the respective contract is concluded only upon an express mutual agreement on all its aspects.
- the sender of this e-mail informs that he/she is not authorized to enter into any contracts on behalf of the company except for cases in which he/she is expressly authorized to do so in writing, and such authorization or power of attorney is submitted to the recipient or the person represented by the recipient, or the existence of such authorization is known to the recipient of the person represented by the recipient.