Reading .csv file while it is being written - python

I have a similar problem to the one described here below in a different question:
Reading from a CSV file while it is being written to
Unfortunately the solution is not explained.
I'd like to create a script that plots some variables in a .csv file dynamically. The .csv is updated everytime a sensor registers something.
My basic idea was to read the file each fixed period of time and if the number of rows is increased, to update the plot with the new variables.
How can I proceed?

I am not that experienced in csv
but take this logic
def writeandRead(one_row):
with open (path/file.csv,"a"): # it is append .. if your case write just change from a to w
write.row(one_row)
with open(whateve.csv,"r"):
red=csv.read #i don't know syntax ... take the logic😊
return red
for row in rows: #or you have a lists whatever dictionary
print(writeandRead(row))

Related

Get different strings from a file and write a .txt

I'am trying to get lines from a text file (.log) into a .txt document.
I need get into my .txt file the same data. But the line itself is sometimes different. From what I have seen on internet, it's usualy done with a pattern that will anticipate how the line is made.
1525:22Player 11 spawned with userinfo: \team\b\forcepowers\0-5-030310001013001131\ip\46.98.134.211:24806\rate\25000\snaps\40\cg_predictItems\1\char_color_blue\34\char_color_green\34\char_color_red\34\color1\65507\color2\14942463\color3\2949375\color4\2949375\handicap\100\jp\0\model\desann/default\name\Faybell\pbindicator\1\saber1\saber_malgus_broken\saber2\none\sex\male\ja_guid\420D990471FC7EB6B3EEA94045F739B7\teamoverlay\1
The line i'm working with usualy looks like this. The data i'am trying to collect are :
\ip\0.0.0.0
\name\NickName_of_the_player
\ja_guid\420D990471FC7EB6B3EEA94045F739B7
And print these data, inside a .txt file. Here is my current code.
As explained above, i'am unsure about what keyword to use for my research on google. And how this could be called (Because the string isn't the same?)
I have been looking around alot, and most of the test I have done, have allowed me to do some things, but i'am not yet able to do as explained above. So i'am in hope for guidance here :) (Sorry if i'am noobish, I understand alot how it works, I just didn't learned language in school, I mostly do small scripts, and usualy they work fine, this time it's way harder)
def readLog(filename):
with open(filename,'r') as eventLog:
data = eventLog.read()
dataList = data.splitlines()
return dataList
eventLog = readLog('games.log')
You'll need to read the files in "raw" mode rather than as strings. When reading the file from disk, use open(filename,'rb'). To use your example, I ran
text_input = r"1525:22Player 11 spawned with userinfo: \team\b\forcepowers\0-5-030310001013001131\ip\46.98.134.211:24806\rate\25000\snaps\40\cg_predictItems\1\char_color_blue\34\char_color_green\34\char_color_red\34\color1\65507\color2\14942463\color3\2949375\color4\2949375\handicap\100\jp\0\model\desann/default\name\Faybell\pbindicator\1\saber1\saber_malgus_broken\saber2\none\sex\male\ja_guid\420D990471FC7EB6B3EEA94045F739B7\teamoverlay\1"
text_as_array = text_input.split('\\')
You'll need to know which columns contain the strings you care about. For example,
with open('output.dat','w') as fil:
fil.write(text_as_array[6])
You can figure these array positions from the sample string
>>> text_as_array[6]
'46.98.134.211:24806'
>>> text_as_array[34]
'Faybell'
>>> text_as_array[44]
'420D990471FC7EB6B3EEA94045F739B7'
If the column positions are not consistent but the key-value pairs are always adjacent, we can leverage that
>>> text_as_array.index("ip")
5
>>> text_as_array[text_as_array.index("ip")+1]
'46.98.134.211:24806'

Parsing two files with Python

I'm still new to python and cannot achieve to make what i'm looking for. I'm using Python 3.7.0
I have one file, called log.csv, containing a log of CANbus messages.
I want to check what is the content of column label Data2 and Data3 when the ID is 348 in column label ID.
If they are both different from "00", I want to make a new string called fault_code with the "Data3+Data2".
Then I want to check on another CSV file where this code string appear, and print the column 6 of this row (label description). But this last part I want to do it only one time per fault_code.
Here is my code:
import csv
CAN_ID = "348"
with open('0.csv') as log:
reader = csv.reader(log,delimiter=',')
for log_row in reader:
if log_row[1] == CAN_ID:
if (log_row[5]+log_row[4]) != "0000":
fault_code = log_row[5]+log_row[4]
with open('Fault_codes.csv') as fault:
readerFC = csv.reader(fault,delimiter=';')
for fault_row in readerFC:
if "0x"+fault_code in readerFC:
print("{fault_row[6]}")
Here is a part of the log.csv file
Timestamp,ID,Data0,Data1,Data2,Data3,Data4,Data5,Data6,Data7,
396774,313,0F,00,28,0A,00,00,C2,FF
396774,314,00,00,06,02,10,00,D8,00
396775,**348**,2C,00,**00,00**,FF,7F,E6,02
and this is a part of faultcode.csv
Level;LED Flashes;UID;FID;Type;Display;Message;Description;RecommendedAction
1;2;1;**0x4481**;Warning;F12001;Handbrake Fault;Handbrake is active;Release handbrake
1;5;1;**0x4541**;Warning;F15001;Fan Fault;blablabla;blablalba
1;5;2;**0x4542**;Warning;F15002;blablabla
Also do you think of a better way to do this task? I've read that Pandas can be very good for large files. As log.csv can have 100'000+ row, it's maybe a better idea to use it. What do you think?
Thank you for your help!
Be careful with your indentation, you get this error because you sometimes you use spaces and other tabs to indent.
As PM 2Ring said, reading 'Fault_codes.csv' everytime you read 1 line of your log is really not efficient.
You should read faultcode once and store the content in RAM (if it fits). You can use pandas to do it, and store the content into a DataFrame. I would do that before reading your logs.
You do not need to store all log.csv lines in RAM. So I'd keep reading it line by line with csv module, do my stuff, write to a new file, and read the next line. No need to use pandas here as it will fill your RAM for nothing.

Constant first row of a .csv file?

I have a Python code which is logging some data into a .csv file.
logging_file = 'test.csv'
dt = datetime.datetime.now()
f = open(logging_file, 'a')
f.write('\n "{:%H:%M:%S}",{},{}'.format(dt,x,y,))
The above code is the core part and this produces continuous data in .csv file as
"00:34:09" ,23.05,23.05
"00:36:09" ,24.05,24.05
"00:38:09" ,26.05,26.05
... etc.,
Now I wish to add the following lines in first row of this data. time, data1,data2.I expect output as
time, data1, data2
"00:34:09" ,23.05,23.05
"00:36:09" ,24.05,24.05
"00:38:09" ,26.05,26.05
... etc.,
I tried many ways. Those ways not produced me the result as preferred format.But I am unable to get my expected result.
Please help me to solve the problem.
I would recommend writing a class specifically for creating and managing logs.Have it initialize a file, on creation, with the expected first line (don't forget a \n character!), and keep track of any necessary information about that log(the name of the log it created, where it is, etc). You can then have the class 'write' to the log (append the log, really), you can create new logs as necessary, and, you can have it check for existing logs, and make decisions about either updating what is existing, or scrapping it and starting over.

Python - Extract private variables from a function?

I have a function f2(a, b)
It is only ever called by a minimize algorithm which iterates the function for different values of a and b each time. I would like to store these iterations in excel for plotting.
Is it possible to extract these values (i only need to paste them all into excel or a text file) easily? Conventional return and print won't work within f2. Is there any way to extract the values a and b to a public list in the main body some other way?
The algorithm may iterate dozens or hundreds of times.
So far I have tried:
Print to console (can't paste this data into excel easily)
Write to file (csv) within f2, the csv file gets overwritten within the function each time though.
Append the values to a global list.
values = []
def f2(a,b):
values.append((a,b))
#todo: actual function logic goes here
Then you can look at values in the main scope once you're done iterating.
Write to file (csv) within f2, the csv file gets overwritten within the function each time though.
Not if you open the file in append mode:
with open("file.csv", "a") as myfile:

csv.writer returning long strings in each row

I've been having some more problems. After you've modified my code well into this.
import csv
mesta=["Ljubljana","Kranj","Skofja Loka","Trzin"]
opis=["ti","mene","ti mene","ne ti mene"]
delodajalci=["GENI","MOJEDELO","MOJADELNICA","HSE"]
ime=["domen","maja","andraz","sanja"]
datum=["2.1.2014","5.10.2014","11.12.2014","5.5.2014"]
with open('sth.csv','w') as csvfile:
zapis = csv.writer(csvfile)
zapis.writerows(zip(ime,delodajalci,opis,datum,mesta))
I have one aditional question. How do I get each piece of my output to have it's own cell and not have 5 really long rows divided by , signs. Since now my output looks like:
domen,GENI,ti,2.1.2014,Ljubljana
maja,MOJEDELO,mene,5.10.2014,Kranj
andraz,MOJADELNICA,ti mene,11.12.2014,Skofja Loka
sanja,HSE,ne ti mene,5.5.2014,Trzin
I hope you will be able to help me. Thank you in advance. Cheers.
So a csv file (Comma-separated values file) is meant to have commas on really long rows as you indicated. To open the file with each value in a cell, say for excel, if you change the extension of the file to .csv it will likely be taken care of. Otherwise, you may need to import the file and indicate that the separators are commas. If you don't have excel, you can try googling for csv viewer (there are many free versions available). In either case, your output looks correct, I think you just need a bit of help opening the file in your program of choice.

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