I have a large *.txt file that has real numbers. I want to import and Execute the RootMeanSquare function on it, but the output of that function is not a real number.
a.txt:
0.00005589924852471949
0.000036651199287161235
0.000016275882123536572
-4.955137498989977*^-6
-0.00002680629351951319
-0.000048814313574683916
ah=Import["a.txt", "List"];
RootMeanSquare[ah]
Sqrt[7.83436*10^-9 + ("-4.955137498989977*^-6")^2]/Sqrt[6]
In my opinion, the problem is in the number -4.955137498989977*^-6.
Please help me.
thank you.
The import yields a string, so split it and convert to numeric expressions.
ah = ToExpression#StringSplit#Import["a.txt"]
StringSplit splits a string at whitespaces by default.
ToExpression is listable, so it operates on the string list in one step.
Related
I have a file with several lines of data. The fields are not always in the same position/column. I want to search for 2 strings and then show only the field and the data that follows. For example:
{"id":"1111","name":"2222","versionCurrent":"3333","hwVersion":"4444"}
{"id":"5555","name":"6666","hwVersion":"7777"}
I would like to return the following:
"id":"1111","hwVersion":"4444"
"id":"5555","hwVersion":"7777"
I am struggling because the data isn't always in the same position, so I can't chose a column number. I feel I need to search for "id" and "hwVersion" Any help is GREATLY appreciated.
Totally agree with #KamilCuk. More specifically
jq -c '{id: .id, hwVersion: .hwVersion}' <<< '{"id":"1111","name":"2222","versionCurrent":"3333","hwVersion":"4444"}'
Outputs:
{"id":"1111","hwVersion":"4444"}
Not quite the specified output, but valid JSON
More to the point, your input should probably be processed record by record, and my guess is that a two column output with "id" and "hwVersion" would be even easier to parse:
cat << EOF | jq -j '"\(.id)\t\(.hwVersion)\n"'
{"id":"1111","name":"2222","versionCurrent":"3333","hwVersion":"4444"}
{"id":"5555","name":"6666","hwVersion":"7777"}
EOF
Outputs:
1111 4444
5555 7777
Since the data looks like a mapping objects and even corresponding to a JSON format, something like this should do, if you don't mind using Python (which comes with JSON) support:
import json
def get_id_hw(s):
d = json.loads(s)
return '"id":"{}","hwVersion":"{}"'.format(d["id"], d["hwVersion"])
We take a line of input string into s and parse it as JSON into a dictionary d. Then we return a formatted string with double-quoted id and hwVersion strings followed by column and double-quoted value of corresponding key from the previously obtained dict.
We can try this with these test input strings and prints:
# These will be our test inputs.
s1 = '{"id":"1111","name":"2222","versionCurrent":"3333","hwVersion":"4444"}'
s2 = '{"id":"5555","name":"6666","hwVersion":"7777"}'
# we pass and print them here
print(get_id_hw(s1))
print(get_id_hw(s2))
But we can just as well iterate over lines of any input.
If you really wanted to use awk, you could, but it's not the most robust and suitable tool:
awk '{ i = gensub(/.*"id":"([0-9]+)".*/, "\\1", "g")
h = gensub(/.*"id":"([0-9]+)".*/, "\\1", "g")
printf("\"id\":\"%s\",\"hwVersion\":\"%s\"\n"), i, h}' /your/file
Since you mention position is not known and assuming it can be in any order, we use one regex to extract id and the other to get hwVersion, then we print it out in given format. If the values could be something other then decimal digits as in your example, the [0-9]+ but would need to reflect that.
And for the fun if it (this preserves the order) if entries from the file, in sed:
sed -e 's#.*\("\(id\|hwVersion\)":"[0-9]\+"\).*\("\(id\|hwVersion\)":"[0-9]\+"\).*#\1,\3#' file
It looks for two groups of "id" or "hwVersion" followed by :"<DECIMAL_DIGITS>".
I have specific questions for my project
input = "3d6"
I want to convert this string some parts to integer. For instance I want to use input[0] like integer.
How can I do this?
There's two problems here:
How to convert a string to an integer
The most straightforward method is the Atoi (ASCII to integer) function in the strconv package., which will take a string of numeric characters and coerce them into an integer for you.
How to extract meaningful components of a known string pattern
In order to use strconv.Atoi, we need the numeric characters of the input by themselves. There's lots of ways to slice and dice a string.
You can just grab the first and last characters directly - input[:1] and input[2:] are the ticket.
You could split the string into two strings on the character "d". Look at the split method, a member of the strings package.
For more complex problems in this space, regular expressions are used. They're a way to define a pattern the computer can look for. For example, the regular expression ^x(\d+)$ will match on any string that starts with the character x and is followed by one or more numeric characters. It will provide direct access to the numeric characters it found by themselves.
Go has first class support for regular expressions via its regexp package.
For example,
package main
import (
"fmt"
)
func main() {
input := "3d6"
i := int(input[0] - '0')
fmt.Println(i)
}
Playground: https://play.golang.org/p/061miKcXdIF
Output:
3
I have been searching a lot online for a solution to this, but here is my question.
Basically I need to reverse a string of 4 characters: ABCD becomes DCBA.
Here is the start of the program:
import javax.swing.JOptionPane;
String input;
input = JOptionPane.showInputDialog("Enter a string with 4 characters (e.g. ABCD): " );
Thanks
The same way you do it in Java.
String output = new StringBuilder(input).reverse().toString();
You could also use a for loop to loop over the characters and build the String yourself.
I know this is open-ended, but I'm not sure how to go about it.
Say I have the string "FDBFBDFLDJVHVBDVBD" and want to find every sub-string that starts with something like "BDF" and ends with either "EFG" or "EDS", is there an easy way to do this?
You can use re.finditer
>>> import re
>>> s = "FDBFBDFLDJVHVBDVBDBDFEFGEDS"
>>> print [s[a.start(): a.end()] for a in re.finditer('BDF', s)]
['BDF', 'BDF']
find every sub-string that starts with something like "BDF" and ends with either "EFG" or "EDS"
It is a job for a regular expression. To extract all such substrings as a list:
import re
substrings = re.findall(r'BDF.*?E(?:FG|DS)', text)
If a substring might contain newlines then pass flags=re.DOTALL.
Example:
>>> re.findall(r'BDF.*?E(?:FG|DS)', "FDBFBDFLDJVHVBDVBDBDFEFGEDS")
['BDFLDJVHVBDVBDBDFEFG']
.*? is not greedy and therefore the shortest substrings are selected. Remove ?, to get the longest match instead.
Seeing as there is no regex expert here yet, I will propose this solution (BTW I added "BDFEFGEDS" to the end of your string so it would give some results):
import re
s = "FDBFBDFLDJVHVBDVBDBDFEFGEDS"
endings = ['EFG', 'EDS']
matches = []
for ending in endings:
match = re.findall(r'(?=(BDF.*{0}))'.format(ending), s)
matches.extend(match)
print matches
giving the result:
['BDFLDJVHVBDVBDBDFEFG', 'BDFEFG', 'BDFLDJVHVBDVBDBDFEFGEDS', 'BDFEFGEDS']
I have filenames which contain %uXXXX substrings, where XXXX are hexadecimal numbers / digits, for example %u0151, etc. I got these filenames by applying URI.unescape, which was able to replace %XX substrings to the corresponding characters but %uXXXX substrings remained untouched. I would like to replace them with the corresponding Unicode codepoints applying String#gsub. I tried the following, but no success:
"rep%u00fcl%u0151".gsub(/%u([0-9a-fA-F]{4,4})/,'\u\1')
I get this:
"rep\\u00fcl\\u0151"
Instead of this:
"repülő"
Try this code:
string.gsub(/%u([0-9A-F]{4})/i){[$1.hex].pack("U")}
In the comments, cremno has a better faster solution:
string.gsub(/%u([0-9A-F]{4})/i){$1.hex.chr(Encoding::UTF_8)}
In the comments, bobince adds important restrictions, worth reading in full.
Per commenter #cremno's idea, try also this code:
gsub(/%u([0-9A-F]{4})/i) { $1.hex.chr(Encoding::UTF_8) }
For example:
s = "rep%u00fcl%u0151"
s.gsub(/%u([0-9A-F]{4})/i) { $1.hex.chr(Encoding::UTF_8) }
# => "repülő"