Description Usage Arguments Details Value Author(s)
Function to optimize slope, offset and sd for all lines of fixations (extended from original paper)This function uses one slope, offset, sd to fit all lines, and use sum(min y_diff) as target measure for optimization uses.
1 2 3  cat_lines2(params, fit_it = TRUE, data, start_pts, k_bounds, o_bounds,
s_bounds, den_sd_cutoff, den_ratio_cutoff, num_checkFirst = 5,
num_checkLast = 10)

params 
A vector of parameters for optimization, the three values in it refer to slope, offset, and sd 
fit_it 
A bollean variable; if it is TRUE, the function will return fit measure; if it is FALSE, the function will return fit information 
data 
A data.frame storing the fixation data including at least the x_pos and y_pos of each fixation 
start_pts 
A data.frame containing the starting position of each text line. It has three columns:

k_bounds 
A list containing the lower and upper boundaries of slope; default value is [0.1, 0.1] 
o_bounds 
A list containing the lower and upper boundaries of offset; defaul value is [0.5*dist of adjacent text lines, 0.5*dist of adjacent text line]) 
s_bounds 
A list containing the lower and upper boundaries of sd; default value is [1, 20] 
den_sd_cutoff 
A float variable for cutoff threshold for density; If it is Inf, use mean(inv_dnorm(exp(data_den_max))) + 3*sd(inv_dnorm(exp(data_den_max))) as cutoff (99.7% are accepted) 
den_ratio_cutoff 
A float variable for cutoff threshold for density ratio (ratio between the maximum density and second maximum density) 
num_checkFirst 
An integer denoting the number of starting fixations used for checking startreading bound; default value is 5 
num_checkLast 
An integer denoting the number of ending fixations used for checking endreading bound; default value is 10 
This function optimizes the slope, offset and sd for all lines of fixations. It uses sum(min(y_diff)) as fit measure for optimization.
A data.frame including fixation data, and fitting data including fit measures and fitted lines information. It adds the following columns:
line: Text line that each fixation belongs to
y_line: y position of the text line that each fixation is assigned to
y_res: Residualized y position of each fixation y_line + y_res will give the original y position of each fixation
slope: Optimized slope value for all fitted lines
offset: Optimizaed offset value for all fitted lines
sd: Optimized sd value for all fitted lines
fit_den: fitted density value
fit_y_diff: fitted y difference (accumulated y differences between each fixation and the fitted line)
Tao Gong [email protected]
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