Trouble using Numpy genfromtxt

Question

Hi i would like to process a data text file but i seem to be having alot of problems with the code. the text file is as follows

-7                        -9.000000000000002       -3                       622.0582425616101
-6.500000000000001        -9.000000000000002       -3                       622.1498719223513
-6                        -9.000000000000002       -3                       622.2415012830924
-5.5                      -9.000000000000002       -3                       622.3331306438334
-5                        -9.000000000000002       -3                       622.3591843760928
-4.500000000000001        -9.000000000000002       -3                       622.374656812196
-4                        -9.000000000000002       -3                       622.3901292482993
-3.5                      -9.000000000000002       -3                       622.4169574709064

however there are some lines where by there are Nan values such as

6.500000000000001         0                        0.5                      NaN
7                         0                        0.5                      NaN
7.5                       0                        0.5                      NaN
8                         0                        0.5                      NaN
8.5                       0                        0.5                      NaN
9.000000000000002         0                        0.5                      NaN
9.5                       0                        0.5                      NaN
10                        0                        0.5                      NaN
10.5                      0                        0.5                      NaN
11                        0                        0.5                      NaN

The text file is simply XYZ coordinates and the respective temperature. What i intend to do is to mainly focus on the last column which is the temperature and there are 2 different data types which is the 'value' and 'Nan'. I have tried many iterations of genfromtxt but i still keep getting many errors. what i wish to do with the last column is to essentially print the max temp, mean temp, gradient etc. Could someone please help me with my code as i am really new to programming and not sure how to go about it. Any help is greatly appreciated.

As of now this is the code i have

import numpy as np 



data = np.genfromtxt('C:\\Users\\loges\\OneDrive\\Documents\\School\\ME4101A FYP\\temperature600.txt',
             skip_header=0, skip_footer=1,dtype=None)


print("Max Temp :", data.max())

but my return results just show nan

Max Temp : nan
[Finished in 0.9s]

I really hope someone would be able to help me. It will be greatly appreciated.

Mike Müller · Answer 1 · 2017-12-31T12:55:17.593

0

Use np.nanmax:

Return the maximum of an array or maximum along an axis, ignoring any NaNs. When all-NaN slices are encountered a RuntimeWarning is raised and NaN is returned for that slice.

For the mean use np.nanmin.

Example:

print(np.nanmax(data[:, -1]))

Output:

622.41695747090637

edited Dec 31 '17 at 12:55

answered Dec 30 '17 at 17:45

Mike Müller

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Hi i tried your method but i got this instead Max Temp : [ 622.05824256 622.14987192 622.24150128 ..., 81. 81. 81. ] [Finished in 0.9s] does it have to do with the defining of parameters using the genfromtxt function? – Logesh Waran Dec 30 '17 at 18:02
What is the `dtype` of `data`? `print(data.dtype)` – Mike Müller Dec 30 '17 at 18:33
the dtype is float64 – Logesh Waran Dec 31 '17 at 09:50
You need to do only on the temperature, i.e. the last column. See my updated answer. – Mike Müller Dec 31 '17 at 12:56

Trouble using Numpy genfromtxt

1 Answers1