I have a hard time converting this string into an array holding each line as an element.
string =
"03 54 56 34 34
34 54 56 43 34 56
43 56 67 34 34"
I tried string_array= [string.split(/$/)]. However, string_array then only holds one element (the whole string). What am I missing?
Side note: The individual numbers in the string are seperated by one whitespace, however, each end of a line does not contain a whitespace.
You could also use method lines:
string.lines.to_a # => ["03 54 56 34 34\n", "34 54 56 43 34 56\n", "43 56 67 34 34"]
And, you could also use chomp would like to have the new line characters removed:
string.lines.map(&:chomp) # => ["03 54 56 34 34", "34 54 56 43 34 56", "43 56 67 34 34"]
string_array = string.split(/\n/) should do the job.
Related
In the GNU make file, need to have run_options30=Pkts=30. but it's not working.
list = 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58
$(foreach var, $(list),$(eval run_options$(var)=Pkts=$(var) ) )
So i'm issuing a query to mysql and it's returning say 1,000 rows,but each iteration of the program could return a different number of rows. I need to break up (without using a mysql limit) this result set into chunks of 100 rows that i can then programatically iterate through in these 100 row chunks.
So
MySQLOutPut='1 2 3 4 ... 10,000"
I need to turn that into an array that looks like
array[1]="1 2 3 ... 100"
array[2]="101 102 103 ... 200"
etc.
I have no clue how to accomplish this elegantly
Using Charles' data generation:
MySQLOutput=$(seq 1 10000 | tr '\n' ' ')
# the sed command will add a newline after every 100 words
# and the mapfile command will read the lines into an array
mapfile -t MySQLOutSplit < <(
sed -r 's/([^[:blank:]]+ ){100}/&\n/g; $s/\n$//' <<< "$MySQLOutput"
)
echo "${#MySQLOutSplit[#]}"
# 100
echo "${MySQLOutSplit[0]}"
# 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100
echo "${MySQLOutSplit[99]}"
# 9901 9902 9903 9904 9905 9906 9907 9908 9909 9910 9911 9912 9913 9914 9915 9916 9917 9918 9919 9920 9921 9922 9923 9924 9925 9926 9927 9928 9929 9930 9931 9932 9933 9934 9935 9936 9937 9938 9939 9940 9941 9942 9943 9944 9945 9946 9947 9948 9949 9950 9951 9952 9953 9954 9955 9956 9957 9958 9959 9960 9961 9962 9963 9964 9965 9966 9967 9968 9969 9970 9971 9972 9973 9974 9975 9976 9977 9978 9979 9980 9981 9982 9983 9984 9985 9986 9987 9988 9989 9990 9991 9992 9993 9994 9995 9996 9997 9998 9999 10000
Something like this:
# generate content
MySQLOutput=$(seq 1 10000 | tr '\n' ' ') # seq is awful, don't use in real life
# split into a large array, each item stored individually
read -r -a MySQLoutArr <<<"$MySQLOutput"
# add each batch of 100 items into a new array entry
batchSize=100
MySQLoutSplit=( )
for ((i=0; i<${#MySQLoutArr[#]}; i+=batchSize)); do
MySQLoutSplit+=( "${MySQLoutArr[*]:i:batchSize}" )
done
To explain some of the finer points:
read -r -a foo reads contents into an array named foo, split on IFS, up to the next character specified by read -d (none given here, thus reading only a single line). If you wanted each line to be a new array entry, consider IFS=$'\n' read -r -d '' -a foo, which will read each line into an array, terminated at the first NUL in the input stream.
"${foo[*]:i:batchSize}" expands to a list of items in array foo, starting at index i, and taking the next batchSize items, concatenated into a single string with the first character in $IFS used as a separator.
My PPM image contains the following :
P6
1200
670
255
ܒNԪjɝ[؋Cц:̈6y5"r-¼,ֈ?Ԛ_݈̻֬كڕÒɪxڇՄmxɘl܊؇euί\jĩqÿHqAʻKPùG9EʁM͂MO̿PɼLȀMǃOǁLƾH»D5A®>ǷFxCٲ;yFƾIǿJʀL»GڲAʂWǯŐĕх՜џᔡ嚪矱Ԫׄ࠘ĝцQfһψ΅e{ڈڗÖܻԡȜׂӐ}˸_hؖ`u؛dьWЋV̓MͺHυPƽF˂I>ٹ6}>س5>Eiuƻ1
and 40000 more lines of illegible code. Is this an encoding issue?
If you want it in ASCII P3 format, you can use ImageMagick, which is in most Linux distros and available for OSX and Windows,iike this
convert yourFile.ppm -compress none output.ppm
Then it will look like this:
P3
70 46
255
48 47 45 50 48 46 54 50 47 56 51 46 58 51 45 57 50 45 56 48 45 57 49 46
56 48 45 56 48 45 55 47 44 53 45 42 52 44 41 53 45 42 53 45 42 49 45 39
49 46 39 52 49 42 55 52 45 57 54 47 63 58 47 70 63 51 74 66 52 76 65 50
...
...
No, this is completely normal for a mode P6 PPM.
In this mode, only the header is ASCII, the pixels are written as binary data, 8 or 16 bits per sample, pixel interleaved.
It's also possible to have PPM in "plain" or ASCII format, this mode uses P3 as its identifier.
See the PPM spec for more info.
I am trying to solve the Projecteuler #11 but I am running into an error when I'm trying to create a function to calculate the multiplication of every 4 numbers in a column. I am getting an error:
Project11.rb:59:in `sumvertical': undefined method `[]' for nil:NilClass (NoMeth
odError)
I feel like there is something I am easily overlooking here. I appreciate the help!
#project #11 http://projecteuler.net/problem=11
grid="08 02 22 97 38 15 00 40 00 75 04 05 07 78 52 12 50 77 91 08
49 49 99 40 17 81 18 57 60 87 17 40 98 43 69 48 04 56 62 00
81 49 31 73 55 79 14 29 93 71 40 67 53 88 30 03 49 13 36 65
52 70 95 23 04 60 11 42 69 24 68 56 01 32 56 71 37 02 36 91
22 31 16 71 51 67 63 89 41 92 36 54 22 40 40 28 66 33 13 80
24 47 32 60 99 03 45 02 44 75 33 53 78 36 84 20 35 17 12 50
32 98 81 28 64 23 67 10 26 38 40 67 59 54 70 66 18 38 64 70
67 26 20 68 02 62 12 20 95 63 94 39 63 08 40 91 66 49 94 21
24 55 58 05 66 73 99 26 97 17 78 78 96 83 14 88 34 89 63 72
21 36 23 09 75 00 76 44 20 45 35 14 00 61 33 97 34 31 33 95
78 17 53 28 22 75 31 67 15 94 03 80 04 62 16 14 09 53 56 92
16 39 05 42 96 35 31 47 55 58 88 24 00 17 54 24 36 29 85 57
86 56 00 48 35 71 89 07 05 44 44 37 44 60 21 58 51 54 17 58
19 80 81 68 05 94 47 69 28 73 92 13 86 52 17 77 04 89 55 40
04 52 08 83 97 35 99 16 07 97 57 32 16 26 26 79 33 27 98 66
88 36 68 87 57 62 20 72 03 46 33 67 46 55 12 32 63 93 53 69
04 42 16 73 38 25 39 11 24 94 72 18 08 46 29 32 40 62 76 36
20 69 36 41 72 30 23 88 34 62 99 69 82 67 59 85 74 04 36 16
20 73 35 29 78 31 90 01 74 31 49 71 48 86 81 16 23 57 05 54
01 70 54 71 83 51 54 69 16 92 33 48 61 43 52 01 89 19 67 48"
grid=grid.split()
grid=grid.collect {|s| s.to_i}
multiarray=[]
i = 0
e = 19
until e > 400
multiarray << grid[i..e]
i+= 20
e+= 20
end
def sumhorizontal(x) #checks sum of all horizontal 4 elements
sum = 0
x.each {|a|
i=0
e=3
while e < a.length
if a[i..e].inject(:*) > sum
sum = a[i..e].inject(:*)
i += 1
e += 1
else
i += 1
e += 1
end
end
}
return sum
end
def sumvertical(x)
sum = 0
i=0
e=0
while e < x.length #Will break once the end point is longer than the length of an array
until i > 20 #Checks the first column
if x[i][e]*x[i+1][e]*x[i+2][e]*x[i+3][e] > sum #Error is here
sum = x[i][e]*x[i+1][e]*x[i+2][e]*x[i+3][e]
i += 1
else
i += 1
end
end
e += 1 #once you are out of the until statement, it increases e by 1 to check the next column
i = 0 #resets i so it can go back to the zero
end
return sum
end
print sumvertical(multiarray)
The grid has 20 rows. Your loop is actually trying to reach all the way to a 24rd row; that's because it goes through 21 iterations (i starts at 0, and goes until it equals 21), and each iteration reaches 3 beyond the current value of i (when you call x[i+3]). When i is 17, your code will break, because x[i+3][e] is trying to index into the 21st row of x. i+3 is 20, but the highest available index is 19. So what happens is, x[20] returns nil, and then the [] method is called on nil, which generates your error.
Also, the standard library has a transpose method that you can call on your array. If you use it, you just need one method (sumhorizontal). You can get the column sums with sumhorizontal(multiarray.transpose).
One more thing... it looks like you're coming from a procedural language. Ruby has an extensive standard library and coding constructs that can save you a lot of time and keystrokes. There is typically no need to iterate with while loops and index variables in Ruby. sumhorizontal, for instance, can be written like this (it should really be called producthorizontal, though if you're trying to solve Project Euler #11:
def sumhorizontal(x)
x.map { |r| r.each_slice(4).map { |s| s.reduce(:*) }.max }.max
end
Good luck with the rest of your Ruby learning journey!
Why do system objects like nil, true or false have a fixed object id in Ruby. Also I tried printing out the object ids of numbers, they are the same and follow an odd number sequence pattern. Any explanation for this?
[nil,true,false].each { |o| print o.object_id, ' '}
4 2 0 => [nil, true, false]
>> (0..50).each { |i| print i.object_id, ' ' }
1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 55 57 59 61 63 65 67 69 71 73 75 77 79 81 83 85 87 89 91 93 95 97 99 101 => 0..50
The following two links explain the concept behind Ruby's object IDs:
http://www.oreillynet.com/ruby/blog/2006/01/the_ruby_value_1.html
http://www.oreillynet.com/ruby/blog/2006/02/ruby_values_and_object_ids.html
The object ID is calculated from the objects value plus some additional information. From that calculation you can derive the values you are seeing in your examples.