Make awk produce error on non-numeric
I have a program that sums a column in a file:
awk -v col=2 '{sum+=$col}END{print sum}' input-file
However, it has a problem: If you give it a file that doesn't have numeric data, (or if one number is missing) it will interpret it as zero.
I want it to produce an error if one of the fields cannot be parsed as a number.
Here's an example input:
bob 1
dave 2
alice 3.5
foo bar
I want it to produce an error because 'bar' is not a number, rather than ignoring the error.
awk numeric-data
asked 2 hours ago
Nick ODellNick ODell
9942820
add a comment |
I have a program that sums a column in a file:
awk -v col=2 '{sum+=$col}END{print sum}' input-file
However, it has a problem: If you give it a file that doesn't have numeric data, (or if one number is missing) it will interpret it as zero.
I want it to produce an error if one of the fields cannot be parsed as a number.
Here's an example input:
bob 1
dave 2
alice 3.5
foo bar
I want it to produce an error because 'bar' is not a number, rather than ignoring the error.
awk numeric-data
asked 2 hours ago
Nick ODellNick ODell
9942820
2
If not a dupe, at least strongly related: Can I determine type of an awk variable?
– Kusalananda
2 hours ago
by "produce an error", do you mean stop altogether, or skip the line, and/or emit a message?
– Jeff Schaller
2 hours ago
Stop altogether and emit a message.
– Nick ODell
2 hours ago
@Kusalananda Thanks, that was really helpful.
– Nick ODell
2 hours ago
add a comment |
I have a program that sums a column in a file:
awk -v col=2 '{sum+=$col}END{print sum}' input-file
However, it has a problem: If you give it a file that doesn't have numeric data, (or if one number is missing) it will interpret it as zero.
I want it to produce an error if one of the fields cannot be parsed as a number.
Here's an example input:
bob 1
dave 2
alice 3.5
foo bar
I want it to produce an error because 'bar' is not a number, rather than ignoring the error.
awk numeric-data
asked 2 hours ago
Nick ODellNick ODell
9942820
I have a program that sums a column in a file:
awk -v col=2 '{sum+=$col}END{print sum}' input-file
However, it has a problem: If you give it a file that doesn't have numeric data, (or if one number is missing) it will interpret it as zero.
I want it to produce an error if one of the fields cannot be parsed as a number.
Here's an example input:
bob 1
dave 2
alice 3.5
foo bar
I want it to produce an error because 'bar' is not a number, rather than ignoring the error.
awk numeric-data
awk numeric-data
asked 2 hours ago
Nick ODellNick ODell
9942820
asked 2 hours ago
Nick ODellNick ODell
9942820
asked 2 hours ago
Nick ODellNick ODell
9942820
asked 2 hours ago
Nick ODellNick ODell
9942820
asked 2 hours ago
Nick ODellNick ODell
9942820
9942820
2
If not a dupe, at least strongly related: Can I determine type of an awk variable?
– Kusalananda
2 hours ago
by "produce an error", do you mean stop altogether, or skip the line, and/or emit a message?
– Jeff Schaller
2 hours ago
Stop altogether and emit a message.
– Nick ODell
2 hours ago
@Kusalananda Thanks, that was really helpful.
– Nick ODell
2 hours ago
add a comment |
2
If not a dupe, at least strongly related: Can I determine type of an awk variable?
– Kusalananda
2 hours ago
by "produce an error", do you mean stop altogether, or skip the line, and/or emit a message?
– Jeff Schaller
2 hours ago
Stop altogether and emit a message.
– Nick ODell
2 hours ago
@Kusalananda Thanks, that was really helpful.
– Nick ODell
2 hours ago
2
2
If not a dupe, at least strongly related: Can I determine type of an awk variable?
– Kusalananda
2 hours ago
If not a dupe, at least strongly related: Can I determine type of an awk variable?
– Kusalananda
2 hours ago
by "produce an error", do you mean stop altogether, or skip the line, and/or emit a message?
– Jeff Schaller
2 hours ago
by "produce an error", do you mean stop altogether, or skip the line, and/or emit a message?
– Jeff Schaller
2 hours ago
Stop altogether and emit a message.
– Nick ODell
2 hours ago
Stop altogether and emit a message.
– Nick ODell
2 hours ago
@Kusalananda Thanks, that was really helpful.
– Nick ODell
2 hours ago
@Kusalananda Thanks, that was really helpful.
– Nick ODell
2 hours ago
add a comment |
3 Answers
3
active
oldest
votes
A reasonable way to test would be to compare the field using tests similar to strtod, which is the method that awk uses to convert strings to numbers:
$2 !~ / *[+-]?[[:digit:]]/ { print "NAN: " $2; exit 1; }
The above differs from strtod in that it does not consider INFINITY or NAN to be "numbers". The leading space requirement could be relaxed under awk's default field-splitting behavior -- meaning the fields would never contain leading space:
$2 !~ /[+-]?[[:digit:]]/ { print "NAN: " $2; exit 1; }
Another option would be to force a numeric conversion, then compare it to zero and then further compare the original input to zero:
{ number=0 + $2;
if (!number && $2 !~ /^[+-]?0*.?0*$/)
print "NAN: "$2;
}
answered 2 hours ago
Jeff SchallerJeff Schaller
39.3k1054125
add a comment |
If you give it a file that doesn't have numeric data,
$col ~ /[^-.[:digit:]]/ {print "Error, non-numeric :"; print $col; exit 1};
Explanation just use a RegEx to check for the presence of characters which are not digits nor floating point, sign, etc.
(or if one number is missing)
add
|| ($col == "")
or
|| (length($col) == 0)
to the rule.
Or you could use a comparison to NF if it's the last column like in your example.
answered 2 hours ago
DrYakDrYak
1814
New contributor
DrYak is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
add a comment |
I ended up with this:
awk -v col=$col '
typeof($col) != "strnum" {
print "Error on line " NR ": " $col " is not numeric"
noprint=1
exit 1
}
{
sum+=$col
}
END {
if(!noprint)
print sum
}' $file
This uses typeof, which is a GNU awk extension. typeof($col) returns 'strnum' if $col is a valid number, and 'string' or 'unassigned' if it is not.
See Can I determine type of an awk variable?
answered 2 hours ago
Nick ODellNick ODell
9942820
add a comment |
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3 Answers
3
active
oldest
votes
3 Answers
3
active
oldest
votes
active
oldest
votes
active
oldest
votes
A reasonable way to test would be to compare the field using tests similar to strtod, which is the method that awk uses to convert strings to numbers:
$2 !~ / *[+-]?[[:digit:]]/ { print "NAN: " $2; exit 1; }
The above differs from strtod in that it does not consider INFINITY or NAN to be "numbers". The leading space requirement could be relaxed under awk's default field-splitting behavior -- meaning the fields would never contain leading space:
$2 !~ /[+-]?[[:digit:]]/ { print "NAN: " $2; exit 1; }
Another option would be to force a numeric conversion, then compare it to zero and then further compare the original input to zero:
{ number=0 + $2;
if (!number && $2 !~ /^[+-]?0*.?0*$/)
print "NAN: "$2;
}
answered 2 hours ago
Jeff SchallerJeff Schaller
39.3k1054125
add a comment |
A reasonable way to test would be to compare the field using tests similar to strtod, which is the method that awk uses to convert strings to numbers:
$2 !~ / *[+-]?[[:digit:]]/ { print "NAN: " $2; exit 1; }
The above differs from strtod in that it does not consider INFINITY or NAN to be "numbers". The leading space requirement could be relaxed under awk's default field-splitting behavior -- meaning the fields would never contain leading space:
$2 !~ /[+-]?[[:digit:]]/ { print "NAN: " $2; exit 1; }
Another option would be to force a numeric conversion, then compare it to zero and then further compare the original input to zero:
{ number=0 + $2;
if (!number && $2 !~ /^[+-]?0*.?0*$/)
print "NAN: "$2;
}
answered 2 hours ago
Jeff SchallerJeff Schaller
39.3k1054125
add a comment |
A reasonable way to test would be to compare the field using tests similar to strtod, which is the method that awk uses to convert strings to numbers:
$2 !~ / *[+-]?[[:digit:]]/ { print "NAN: " $2; exit 1; }
The above differs from strtod in that it does not consider INFINITY or NAN to be "numbers". The leading space requirement could be relaxed under awk's default field-splitting behavior -- meaning the fields would never contain leading space:
$2 !~ /[+-]?[[:digit:]]/ { print "NAN: " $2; exit 1; }
Another option would be to force a numeric conversion, then compare it to zero and then further compare the original input to zero:
{ number=0 + $2;
if (!number && $2 !~ /^[+-]?0*.?0*$/)
print "NAN: "$2;
}
answered 2 hours ago
Jeff SchallerJeff Schaller
39.3k1054125
A reasonable way to test would be to compare the field using tests similar to strtod, which is the method that awk uses to convert strings to numbers:
$2 !~ / *[+-]?[[:digit:]]/ { print "NAN: " $2; exit 1; }
The above differs from strtod in that it does not consider INFINITY or NAN to be "numbers". The leading space requirement could be relaxed under awk's default field-splitting behavior -- meaning the fields would never contain leading space:
$2 !~ /[+-]?[[:digit:]]/ { print "NAN: " $2; exit 1; }
Another option would be to force a numeric conversion, then compare it to zero and then further compare the original input to zero:
{ number=0 + $2;
if (!number && $2 !~ /^[+-]?0*.?0*$/)
print "NAN: "$2;
}
answered 2 hours ago
Jeff SchallerJeff Schaller
39.3k1054125
edited 2 hours ago
answered 2 hours ago
Jeff SchallerJeff Schaller
39.3k1054125
answered 2 hours ago
Jeff SchallerJeff Schaller
39.3k1054125
answered 2 hours ago
Jeff SchallerJeff Schaller
39.3k1054125
39.3k1054125
add a comment |
add a comment |
If you give it a file that doesn't have numeric data,
$col ~ /[^-.[:digit:]]/ {print "Error, non-numeric :"; print $col; exit 1};
Explanation just use a RegEx to check for the presence of characters which are not digits nor floating point, sign, etc.
(or if one number is missing)
add
|| ($col == "")
or
|| (length($col) == 0)
to the rule.
Or you could use a comparison to NF if it's the last column like in your example.
answered 2 hours ago
DrYakDrYak
1814
New contributor
DrYak is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
add a comment |
If you give it a file that doesn't have numeric data,
$col ~ /[^-.[:digit:]]/ {print "Error, non-numeric :"; print $col; exit 1};
Explanation just use a RegEx to check for the presence of characters which are not digits nor floating point, sign, etc.
(or if one number is missing)
add
|| ($col == "")
or
|| (length($col) == 0)
to the rule.
Or you could use a comparison to NF if it's the last column like in your example.
answered 2 hours ago
DrYakDrYak
1814
New contributor
DrYak is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
add a comment |
If you give it a file that doesn't have numeric data,
$col ~ /[^-.[:digit:]]/ {print "Error, non-numeric :"; print $col; exit 1};
Explanation just use a RegEx to check for the presence of characters which are not digits nor floating point, sign, etc.
(or if one number is missing)
add
|| ($col == "")
or
|| (length($col) == 0)
to the rule.
Or you could use a comparison to NF if it's the last column like in your example.
answered 2 hours ago
DrYakDrYak
1814
New contributor
DrYak is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
If you give it a file that doesn't have numeric data,
$col ~ /[^-.[:digit:]]/ {print "Error, non-numeric :"; print $col; exit 1};
Explanation just use a RegEx to check for the presence of characters which are not digits nor floating point, sign, etc.
(or if one number is missing)
add
|| ($col == "")
or
|| (length($col) == 0)
to the rule.
Or you could use a comparison to NF if it's the last column like in your example.
answered 2 hours ago
DrYakDrYak
1814
New contributor
DrYak is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
answered 2 hours ago
DrYakDrYak
1814
New contributor
DrYak is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
answered 2 hours ago
DrYakDrYak
1814
answered 2 hours ago
DrYakDrYak
1814
1814
New contributor
DrYak is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
DrYak is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
DrYak is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
add a comment |
add a comment |
I ended up with this:
awk -v col=$col '
typeof($col) != "strnum" {
print "Error on line " NR ": " $col " is not numeric"
noprint=1
exit 1
}
{
sum+=$col
}
END {
if(!noprint)
print sum
}' $file
This uses typeof, which is a GNU awk extension. typeof($col) returns 'strnum' if $col is a valid number, and 'string' or 'unassigned' if it is not.
See Can I determine type of an awk variable?
answered 2 hours ago
Nick ODellNick ODell
9942820
add a comment |
I ended up with this:
awk -v col=$col '
typeof($col) != "strnum" {
print "Error on line " NR ": " $col " is not numeric"
noprint=1
exit 1
}
{
sum+=$col
}
END {
if(!noprint)
print sum
}' $file
This uses typeof, which is a GNU awk extension. typeof($col) returns 'strnum' if $col is a valid number, and 'string' or 'unassigned' if it is not.
See Can I determine type of an awk variable?
answered 2 hours ago
Nick ODellNick ODell
9942820
add a comment |
I ended up with this:
awk -v col=$col '
typeof($col) != "strnum" {
print "Error on line " NR ": " $col " is not numeric"
noprint=1
exit 1
}
{
sum+=$col
}
END {
if(!noprint)
print sum
}' $file
This uses typeof, which is a GNU awk extension. typeof($col) returns 'strnum' if $col is a valid number, and 'string' or 'unassigned' if it is not.
See Can I determine type of an awk variable?
answered 2 hours ago
Nick ODellNick ODell
9942820
I ended up with this:
awk -v col=$col '
typeof($col) != "strnum" {
print "Error on line " NR ": " $col " is not numeric"
noprint=1
exit 1
}
{
sum+=$col
}
END {
if(!noprint)
print sum
}' $file
This uses typeof, which is a GNU awk extension. typeof($col) returns 'strnum' if $col is a valid number, and 'string' or 'unassigned' if it is not.
See Can I determine type of an awk variable?
answered 2 hours ago
Nick ODellNick ODell
9942820
answered 2 hours ago
Nick ODellNick ODell
9942820
answered 2 hours ago
Nick ODellNick ODell
9942820
answered 2 hours ago
Nick ODellNick ODell
9942820
9942820
add a comment |
add a comment |
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2
If not a dupe, at least strongly related: Can I determine type of an awk variable?
– Kusalananda
2 hours ago
by "produce an error", do you mean stop altogether, or skip the line, and/or emit a message?
– Jeff Schaller
2 hours ago
Stop altogether and emit a message.
– Nick ODell
2 hours ago
@Kusalananda Thanks, that was really helpful.
– Nick ODell
2 hours ago