使用python将宽格式csv转换为长格式csv

Question

I have some trouble to convert my csv data from a wide table format csv to a long format csv in python. At the moment it looks like this:

Time Temp1 Temp2 Temp3 Temp4 Temp5
00   21     32   33    21    23
10   34     23   12    08    23
20   12     54   33    54    55

Now I like to transform this data into a long data format. Something like this:

00 temp1 21
00 temp2 32
00 temp3 33
00 temp4 21
00 temp5 23
10 temp1 34 
10 temp2 23
10 temp3 12
10 temp4 08
10 temp5 23
20 temp1 12
20 temp2 54
.
.
.

Any help on how to attack such a problem in python would be really helpful.

Answer 1

You can use the csv module but the logic is the same.

with open("in.csv") as f,open("out.csv","w") as out:
     headers = next(f).split()[1:]  # keep headers/Time Temp1 Temp2 Temp3 Temp4 Temp5
     for row in f:
        row = row.split()
        time = row[0]
        data = zip(headers, row[1:]) # match correct temp to row item
        for a, b in data:
            out.write("{} {} {}\n".format(time,a.lower(),b))
            print("{} {} {}".format(time,a.lower(),b))


00 temp1 21
00 temp2 32
00 temp3 33
00 temp4 21
00 temp5 23
10 temp1 34
10 temp2 23
10 temp3 12
10 temp4 08
10 temp5 23
20 temp1 12
20 temp2 54
20 temp3 33
20 temp4 54
20 temp5 55

out.csv:

00 temp1 21
00 temp2 32
00 temp3 33
00 temp4 21
00 temp5 23
10 temp1 34
10 temp2 23
10 temp3 12
10 temp4 08
10 temp5 23
20 temp1 12
20 temp2 54
20 temp3 33
20 temp4 54
20 temp5 55

Answer 2

Try using pandas Dataframe for storing the data of the csv file. It provides an inbuilt function pandas.melt which would be useful for your problem.

Here is the link to the documentation.