Question

我有一个字符数组dat，我想将其转换为数据帧df，但它不起作用

 head(dat)
[1] "   1931   1    5.0     0.6      11    78.4    43.4"
[2] "   1931   2    6.7     0.7       7    48.9    63.6"
[3] "   1931   4   10.4     3.1       3    44.6   110.1"
[4] "   1931   5   13.2     6.1       1    63.7   167.4"
[5] "   1931   6   15.4     8.0       0    87.8   150.3"
[6] "   1931   7   17.3    10.6       0   121.4   111.2"

> df<-as.data.frame(dat)
> head(df)
                                                 dat
1    1931   1    5.0     0.6      11    78.4    43.4
2    1931   2    6.7     0.7       7    48.9    63.6
3    1931   4   10.4     3.1       3    44.6   110.1
4    1931   5   13.2     6.1       1    63.7   167.4
5    1931   6   15.4     8.0       0    87.8   150.3
6    1931   7   17.3    10.6       0   121.4   111.2




df[,c(3)]

[.data.frame（df，，c（3））中的错误：未定义的列已选中

Answer 1

使用read.table阅读：您可以根据需要rename。

df<-read.table(text = "                                                dat
1    1931   1    5.0     0.6      11    78.4    43.4
2    1931   2    6.7     0.7       7    48.9    63.6
3    1931   4   10.4     3.1       3    44.6   110.1
4    1931   5   13.2     6.1       1    63.7   167.4
5    1931   6   15.4     8.0       0    87.8   150.3
6    1931   7   17.3    10.6       0   121.4   111.2",
               header=F,fill=T,as.is=T,skip = 1)
df[3]
 V3
1  1
2  2
3  4
4  5
5  6
6  7

Answer 2

如果dat如结尾处的注释中可重复显示，则as.data.frame(dat)创建一个数据框，其中包含一列称为dat，然后尝试获取第三列由于只有一列，因此会导致错误。

相反，使用read.table并获得第三列，如下所示。如果要获得数据帧结果，请省略逗号。

read.table(text = dat)[, 3]
## [1]  5.0  6.7 10.4 13.2 15.4 17.3

注意

dat <- c("   1931   1    5.0     0.6      11    78.4    43.4",
  "   1931   2    6.7     0.7       7    48.9    63.6",
  "   1931   4   10.4     3.1       3    44.6   110.1",
  "   1931   5   13.2     6.1       1    63.7   167.4",
  "   1931   6   15.4     8.0       0    87.8   150.3",
  "   1931   7   17.3    10.6       0   121.4   111.2")

Answer 3

这是一种from torchvision import datasets, transforms from torch.utils.data import DataLoader import matplotlib.pyplot as plt # Define Image Transform transform = transforms.Compose([transforms.Resize(255), transforms.CenterCrop(224), transforms.ToTensor()]) # Load Custom Image Dataset dataset = datasets.ImageFolder(root="./Cat_Dog_data", transform=transform) # DataLoader dataLoader = DataLoader(dataset=dataset, batch_size=32, shuffle=True) # Get one batch of Data # len(images): 32 # len(labels): 32 # shape of images[0]: torch.Size([3, 224, 224]) images, labels = next(iter(dataLoader)) # img.shape: [224,224,3] img = images[0].numpy().reshape([224, 224, 3]) plt.imshow(img) plt.show()的方法：

tidyverse

这导致：

dat <- c("   1931   1    5.0     0.6      11    78.4    43.4",
         "   1931   2    6.7     0.7       7    48.9    63.6",
         "   1931   4   10.4     3.1       3    44.6   110.1",
         "   1931   5   13.2     6.1       1    63.7   167.4",
         "   1931   6   15.4     8.0       0    87.8   150.3",
         "   1931   7   17.3    10.6       0   121.4   111.2")

library(tidyverse)
str_trim(dat) %>%     # trim leading space
  tibble(x = .) %>%   # put into tibble (data.frame)
  separate(x,         # separate x into 7 columns, named below
           into = c("year","v1","v2","v3","v4","v5","v6"), 
           sep = "[ ]{1,}")  # separate by one or more spaces ("[ ]{1,}")

如何将字符数组转换为数据框

3 个答案:

注意